From 26fcab53e05ce66f5533f0f07ed13d727a891c8d Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 13:40:39 +0200 Subject: Remove unused file --- doc/manual/expressions/builder-syntax.xml | 119 ------------------------------ 1 file changed, 119 deletions(-) delete mode 100644 doc/manual/expressions/builder-syntax.xml (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/builder-syntax.xml b/doc/manual/expressions/builder-syntax.xml deleted file mode 100644 index e51bade44..000000000 --- a/doc/manual/expressions/builder-syntax.xml +++ /dev/null @@ -1,119 +0,0 @@ -
- -Builder Syntax - -Build script for GNU Hello -(<filename>builder.sh</filename>) - -source $stdenv/setup - -PATH=$perl/bin:$PATH - -tar xvfz $src -cd hello-* -./configure --prefix=$out -make -make install - - - shows the builder referenced -from Hello's Nix expression (stored in -pkgs/applications/misc/hello/ex-1/builder.sh). -The builder can actually be made a lot shorter by using the -generic builder functions provided by -stdenv, but here we write out the build steps to -elucidate what a builder does. It performs the following -steps: - - - - - - When Nix runs a builder, it initially completely clears the - environment (except for the attributes declared in the - derivation). For instance, the PATH variable is - emptyActually, it's initialised to - /path-not-set to prevent Bash from setting it - to a default value.. This is done to prevent - undeclared inputs from being used in the build process. If for - example the PATH contained - /usr/bin, then you might accidentally use - /usr/bin/gcc. - - So the first step is to set up the environment. This is - done by calling the setup script of the - standard environment. The environment variable - stdenv points to the location of the standard - environment being used. (It wasn't specified explicitly as an - attribute in , but - mkDerivation adds it automatically.) - - - - - - Since Hello needs Perl, we have to make sure that Perl is in - the PATH. The perl environment - variable points to the location of the Perl package (since it - was passed in as an attribute to the derivation), so - $perl/bin is the - directory containing the Perl interpreter. - - - - - - Now we have to unpack the sources. The - src attribute was bound to the result of - fetching the Hello source tarball from the network, so the - src environment variable points to the location in - the Nix store to which the tarball was downloaded. After - unpacking, we cd to the resulting source - directory. - - The whole build is performed in a temporary directory - created in /tmp, by the way. This directory is - removed after the builder finishes, so there is no need to clean - up the sources afterwards. Also, the temporary directory is - always newly created, so you don't have to worry about files from - previous builds interfering with the current build. - - - - - - GNU Hello is a typical Autoconf-based package, so we first - have to run its configure script. In Nix - every package is stored in a separate location in the Nix store, - for instance - /nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1. - Nix computes this path by cryptographically hashing all attributes - of the derivation. The path is passed to the builder through the - out environment variable. So here we give - configure the parameter - --prefix=$out to cause Hello to be installed in - the expected location. - - - - - - Finally we build Hello (make) and install - it into the location specified by out - (make install). - - - - - -If you are wondering about the absence of error checking on the -result of various commands called in the builder: this is because the -shell script is evaluated with Bash's option, -which causes the script to be aborted if any command fails without an -error check. - -
\ No newline at end of file -- cgit v1.2.3 From c20c0823838d257b1e18e71c307f53afac0d2b39 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 10:38:19 +0200 Subject: -> --- doc/manual/expressions/advanced-attributes.xml | 6 +++--- doc/manual/expressions/build-script.xml | 14 +++++++------- doc/manual/expressions/derivations.xml | 16 ++++++++-------- doc/manual/expressions/generic-builder.xml | 8 ++++---- doc/manual/expressions/language-values.xml | 2 +- doc/manual/expressions/simple-building-testing.xml | 2 +- 6 files changed, 24 insertions(+), 24 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/advanced-attributes.xml b/doc/manual/expressions/advanced-attributes.xml index 5759ff50e..3a0413ceb 100644 --- a/doc/manual/expressions/advanced-attributes.xml +++ b/doc/manual/expressions/advanced-attributes.xml @@ -139,7 +139,7 @@ impureEnvVars = [ "http_proxy" "https_proxy" ... ]; to make it use the proxy server configuration specified by the - user in the environment variables http_proxy and + user in the environment variables http_proxy and friends. This attribute is only allowed in then when the builder runs, the environment variable - bigPath will contain the absolute path to a + bigPath will contain the absolute path to a temporary file containing a very long string. That is, for any attribute x listed in passAsFile, Nix will pass an environment - variable xPath holding + variable xPath holding the path of the file containing the value of attribute x. This is useful when you need to pass large strings to a builder, since most operating systems impose a diff --git a/doc/manual/expressions/build-script.xml b/doc/manual/expressions/build-script.xml index 7bad8f808..44264239d 100644 --- a/doc/manual/expressions/build-script.xml +++ b/doc/manual/expressions/build-script.xml @@ -35,19 +35,19 @@ steps: When Nix runs a builder, it initially completely clears the environment (except for the attributes declared in the - derivation). For instance, the PATH variable is + derivation). For instance, the PATH variable is emptyActually, it's initialised to /path-not-set to prevent Bash from setting it to a default value.. This is done to prevent undeclared inputs from being used in the build process. If for - example the PATH contained + example the PATH contained /usr/bin, then you might accidentally use /usr/bin/gcc. So the first step is to set up the environment. This is done by calling the setup script of the standard environment. The environment variable - stdenv points to the location of the standard + stdenv points to the location of the standard environment being used. (It wasn't specified explicitly as an attribute in , but mkDerivation adds it automatically.) @@ -57,7 +57,7 @@ steps: Since Hello needs Perl, we have to make sure that Perl is in - the PATH. The perl environment + the PATH. The perl environment variable points to the location of the Perl package (since it was passed in as an attribute to the derivation), so $perl/bin is the @@ -70,7 +70,7 @@ steps: Now we have to unpack the sources. The src attribute was bound to the result of fetching the Hello source tarball from the network, so the - src environment variable points to the location in + src environment variable points to the location in the Nix store to which the tarball was downloaded. After unpacking, we cd to the resulting source directory. @@ -93,7 +93,7 @@ steps: /nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1. Nix computes this path by cryptographically hashing all attributes of the derivation. The path is passed to the builder through the - out environment variable. So here we give + out environment variable. So here we give configure the parameter --prefix=$out to cause Hello to be installed in the expected location. @@ -103,7 +103,7 @@ steps: Finally we build Hello (make) and install - it into the location specified by out + it into the location specified by out (make install). diff --git a/doc/manual/expressions/derivations.xml b/doc/manual/expressions/derivations.xml index 6f6297565..a11de0088 100644 --- a/doc/manual/expressions/derivations.xml +++ b/doc/manual/expressions/derivations.xml @@ -122,7 +122,7 @@ the Nixpkgs manual for details. A temporary directory is created under the directory - specified by TMPDIR (default + specified by TMPDIR (default /tmp) where the build will take place. The current directory is changed to this directory. @@ -133,29 +133,29 @@ the Nixpkgs manual for details. - NIX_BUILD_TOP contains the path of + NIX_BUILD_TOP contains the path of the temporary directory for this build. - Also, TMPDIR, - TEMPDIR, TMP, TEMP + Also, TMPDIR, + TEMPDIR, TMP, TEMP are set to point to the temporary directory. This is to prevent the builder from accidentally writing temporary files anywhere else. Doing so might cause interference by other processes. - PATH is set to + PATH is set to /path-not-set to prevent shells from initialising it to their built-in default value. - HOME is set to + HOME is set to /homeless-shelter to prevent programs from using /etc/passwd or the like to find the user's home directory, which could cause impurity. Usually, when - HOME is set, it is used as the location of the home + HOME is set, it is used as the location of the home directory, even if it points to a non-existent path. - NIX_STORE is set to the path of the + NIX_STORE is set to the path of the top-level Nix store directory (typically, /nix/store). diff --git a/doc/manual/expressions/generic-builder.xml b/doc/manual/expressions/generic-builder.xml index db7ff405d..16b0268a7 100644 --- a/doc/manual/expressions/generic-builder.xml +++ b/doc/manual/expressions/generic-builder.xml @@ -38,18 +38,18 @@ genericBuild - The buildInputs variable tells + The buildInputs variable tells setup to use the indicated packages as inputs. This means that if a package provides a bin subdirectory, it's added to - PATH; if it has a include + PATH; if it has a include subdirectory, it's added to GCC's header search path; and so on.How does it work? setup tries to source the file pkg/nix-support/setup-hook of all dependencies. These “setup hooks” can then set up whatever environment variables they want; for instance, the setup hook for - Perl sets the PERL5LIB environment variable to + Perl sets the PERL5LIB environment variable to contain the lib/site_perl directories of all inputs. @@ -78,7 +78,7 @@ genericBuild Discerning readers will note that the -buildInputs could just as well have been set in the Nix +buildInputs could just as well have been set in the Nix expression, like this: diff --git a/doc/manual/expressions/language-values.xml b/doc/manual/expressions/language-values.xml index bb2090c88..4a72c67a8 100644 --- a/doc/manual/expressions/language-values.xml +++ b/doc/manual/expressions/language-values.xml @@ -176,7 +176,7 @@ stdenv.mkDerivation { Paths can also be specified between angle brackets, e.g. <nixpkgs>. This means that the directories listed in the environment variable - NIX_PATH will be searched + NIX_PATH will be searched for the given file or directory name. diff --git a/doc/manual/expressions/simple-building-testing.xml b/doc/manual/expressions/simple-building-testing.xml index ce0a1636d..33a802e83 100644 --- a/doc/manual/expressions/simple-building-testing.xml +++ b/doc/manual/expressions/simple-building-testing.xml @@ -45,7 +45,7 @@ name. Nix has transactional semantics. Once a build finishes successfully, Nix makes a note of this in its database: it registers -that the path denoted by out is now +that the path denoted by out is now valid. If you try to build the derivation again, Nix will see that the path is already valid and finish immediately. If a build fails, either because it returns a non-zero exit code, because -- cgit v1.2.3 From 13df1faf25769924dae07e65f3ef3ffdd66f10ee Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 13:58:49 +0200 Subject: Get rid of callouts since Markdown doesn't support them --- doc/manual/expressions/arguments-variables.xml | 51 ++++++++---------- doc/manual/expressions/build-script.xml | 48 ++++++++--------- doc/manual/expressions/builtins.xml | 72 +++++++++++--------------- doc/manual/expressions/expression-syntax.xml | 48 ++++++++--------- doc/manual/expressions/generic-builder.xml | 34 ++++++------ doc/manual/expressions/language-constructs.xml | 36 ++++++------- 6 files changed, 134 insertions(+), 155 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/arguments-variables.xml b/doc/manual/expressions/arguments-variables.xml index bf60cb7ee..a4375c777 100644 --- a/doc/manual/expressions/arguments-variables.xml +++ b/doc/manual/expressions/arguments-variables.xml @@ -6,20 +6,25 @@ Arguments and Variables - +The Nix expression in is a +function; it is missing some arguments that have to be filled in +somewhere. In the Nix Packages collection this is done in the file +pkgs/top-level/all-packages.nix, where all Nix +expressions for packages are imported and called with the appropriate +arguments. Here are some fragments of +all-packages.nix, with annotations of what they +mean: -Composing GNU Hello -(<filename>all-packages.nix</filename>) ... -rec { +rec { ① - hello = import ../applications/misc/hello/ex-1 { + hello = import ../applications/misc/hello/ex-1 ② { ③ inherit fetchurl stdenv perl; }; - perl = import ../development/interpreters/perl { + perl = import ../development/interpreters/perl { ④ inherit fetchurl stdenv; }; @@ -31,31 +36,19 @@ rec { } - -The Nix expression in is a -function; it is missing some arguments that have to be filled in -somewhere. In the Nix Packages collection this is done in the file -pkgs/top-level/all-packages.nix, where all -Nix expressions for packages are imported and called with the -appropriate arguments. shows -some fragments of -all-packages.nix. - - - - + + This file defines a set of attributes, all of which are concrete derivations (i.e., not functions). In fact, we define a mutually recursive set of attributes. That is, the attributes can refer to each other. This is precisely what we want since we want to plug the various packages into each other. + - - - + Here we import the Nix expression for GNU Hello. The import operation just loads and returns the @@ -71,9 +64,9 @@ some fragments of When you try to import a directory, Nix automatically appends /default.nix to the file name. - + - + This is where the actual composition takes place. Here we call the function imported from @@ -107,15 +100,15 @@ hello = callPackage ../applications/misc/hello/ex-1 { stdenv = myStdenv; }; - + - + Likewise, we have to instantiate Perl, fetchurl, and the standard environment. - + - + - \ No newline at end of file + diff --git a/doc/manual/expressions/build-script.xml b/doc/manual/expressions/build-script.xml index 44264239d..892274f50 100644 --- a/doc/manual/expressions/build-script.xml +++ b/doc/manual/expressions/build-script.xml @@ -6,32 +6,30 @@ Build Script -Build script for GNU Hello -(<filename>builder.sh</filename>) +Here is the builder referenced +from Hello's Nix expression (stored in +pkgs/applications/misc/hello/ex-1/builder.sh): + -source $stdenv/setup +source $stdenv/setup ① -PATH=$perl/bin:$PATH +PATH=$perl/bin:$PATH ② -tar xvfz $src +tar xvfz $src ③ cd hello-* -./configure --prefix=$out -make +./configure --prefix=$out ④ +make ⑤ make install - - shows the builder referenced -from Hello's Nix expression (stored in -pkgs/applications/misc/hello/ex-1/builder.sh). -The builder can actually be made a lot shorter by using the +The builder can actually be made a lot shorter by using the generic builder functions provided by stdenv, but here we write out the build steps to elucidate what a builder does. It performs the following steps: - + - + When Nix runs a builder, it initially completely clears the environment (except for the attributes declared in the @@ -52,9 +50,9 @@ steps: attribute in , but mkDerivation adds it automatically.) - + - + Since Hello needs Perl, we have to make sure that Perl is in the PATH. The perl environment @@ -63,9 +61,9 @@ steps: $perl/bin is the directory containing the Perl interpreter. - + - + Now we have to unpack the sources. The src attribute was bound to the result of @@ -82,9 +80,9 @@ steps: always newly created, so you don't have to worry about files from previous builds interfering with the current build. - + - + GNU Hello is a typical Autoconf-based package, so we first have to run its configure script. In Nix @@ -98,17 +96,17 @@ steps: --prefix=$out to cause Hello to be installed in the expected location. - + - + Finally we build Hello (make) and install it into the location specified by out (make install). - + - + If you are wondering about the absence of error checking on the result of various commands called in the builder: this is because the @@ -116,4 +114,4 @@ shell script is evaluated with Bash's option, which causes the script to be aborted if any command fails without an error check. - \ No newline at end of file + diff --git a/doc/manual/expressions/builtins.xml b/doc/manual/expressions/builtins.xml index a18c5801a..478b67ce8 100644 --- a/doc/manual/expressions/builtins.xml +++ b/doc/manual/expressions/builtins.xml @@ -1511,39 +1511,9 @@ in foo - shows an example where this is - the case. The builder is supposed to generate the configuration - file for a Jetty - servlet container. A servlet container contains a number - of servlets (*.war files) each exported under - a specific URI prefix. So the servlet configuration is a list of - sets containing the path and - war of the servlet (). This kind of information is - difficult to communicate with the normal method of passing - information through an environment variable, which just - concatenates everything together into a string (which might just - work in this case, but wouldn’t work if fields are optional or - contain lists themselves). Instead the Nix expression is - converted to an XML representation with - toXML, which is unambiguous and can easily be - processed with the appropriate tools. For instance, in the - example an XSLT stylesheet () is applied to it () to - generate the XML configuration file for the Jetty server. The XML - representation produced from by toXML is shown in . - - Note that uses the toFile built-in to write the - builder and the stylesheet “inline” in the Nix expression. The - path of the stylesheet is spliced into the builder at - xsltproc ${stylesheet} - .... - - Passing information to a builder - using <function>toXML</function> + Here is an example where this is + the case: + $out/server-conf.xml]]> $out/server-conf.xml]]> ① ② @@ -1575,16 +1545,32 @@ stdenv.mkDerivation (rec { "; - servlets = builtins.toXML []]> ③ - - - XML representation produced by - <function>toXML</function> + The builder is supposed to generate the configuration file + for a Jetty servlet + container. A servlet container contains a number of + servlets (*.war files) each exported under a + specific URI prefix. So the servlet configuration is a list of + sets containing the path and + war of the servlet (). This kind of information is + difficult to communicate with the normal method of passing + information through an environment variable, which just + concatenates everything together into a string (which might just + work in this case, but wouldn’t work if fields are optional or + contain lists themselves). Instead the Nix expression is + converted to an XML representation with + toXML, which is unambiguous and can easily be + processed with the appropriate tools. For instance, in the + example an XSLT stylesheet (at point ②) is applied to it (at point + ①) to generate the XML configuration file for the Jetty server. + The XML representation produced at point ③ by + toXML is as follows: @@ -1608,7 +1594,11 @@ stdenv.mkDerivation (rec { ]]> - + Note that uses the toFile built-in to write the + builder and the stylesheet “inline” in the Nix expression. The + path of the stylesheet is spliced into the builder using the + syntax xsltproc ${stylesheet}. diff --git a/doc/manual/expressions/expression-syntax.xml b/doc/manual/expressions/expression-syntax.xml index a3de20713..562a9e9f4 100644 --- a/doc/manual/expressions/expression-syntax.xml +++ b/doc/manual/expressions/expression-syntax.xml @@ -6,33 +6,31 @@ Expression Syntax -Nix expression for GNU Hello -(<filename>default.nix</filename>) +Here is a Nix expression for GNU Hello: + -{ stdenv, fetchurl, perl }: +{ stdenv, fetchurl, perl }: ① -stdenv.mkDerivation { - name = "hello-2.1.1"; - builder = ./builder.sh; - src = fetchurl { +stdenv.mkDerivation { ② + name = "hello-2.1.1"; ③ + builder = ./builder.sh; ④ + src = fetchurl { ⑤ url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; }; - inherit perl; + inherit perl; ⑥ } - - shows a Nix expression for GNU -Hello. It's actually already in the Nix Packages collection in +This file is actually already in the Nix Packages collection in pkgs/applications/misc/hello/ex-1/default.nix. It is customary to place each package in a separate directory and call the single Nix expression in that directory default.nix. The file has the following elements (referenced from the figure by number): - + - + This states that the expression is a function that expects to be called with three @@ -57,9 +55,9 @@ the single Nix expression in that directory function; when given the required arguments, the body should describe how to build an instance of the Hello package. - + - + So we have to build a package. Building something from other stuff is called a derivation in Nix (as @@ -76,9 +74,9 @@ the single Nix expression in that directory nameN = exprN; }. - + - + The attribute name specifies the symbolic name and version of the package. Nix doesn't really care about @@ -87,9 +85,9 @@ the single Nix expression in that directory packages. This attribute is required by mkDerivation. - + - + The attribute builder specifies the builder. This attribute can sometimes be omitted, in which case @@ -101,9 +99,9 @@ the single Nix expression in that directory ./builder.sh refers to the shell script shown in , discussed below. - + - + The builder has to know what the sources of the package are. Here, the attribute src is bound to the @@ -120,9 +118,9 @@ the single Nix expression in that directory customary, and it's also expected by the default builder (which we don't use in this example). - + - + Since the derivation requires Perl, we have to pass the value of the perl function argument to the @@ -139,9 +137,9 @@ perl = perl; causes the specified attributes to be bound to whatever variables with the same name happen to be in scope. - + - + diff --git a/doc/manual/expressions/generic-builder.xml b/doc/manual/expressions/generic-builder.xml index 16b0268a7..71b342f99 100644 --- a/doc/manual/expressions/generic-builder.xml +++ b/doc/manual/expressions/generic-builder.xml @@ -20,23 +20,21 @@ make install The builders for almost all Unix packages look like this — set up some environment variables, unpack the sources, configure, build, and install. For this reason the standard environment provides some Bash -functions that automate the build process. A builder using the -generic build facilities in shown in . +functions that automate the build process. Here is what a builder +using the generic build facilities looks like: -Build script using the generic -build functions -buildInputs="$perl" +buildInputs="$perl" ① -source $stdenv/setup +source $stdenv/setup ② -genericBuild - +genericBuild ③ - +Here is what each line means: - + + + The buildInputs variable tells setup to use the indicated packages as @@ -54,16 +52,16 @@ genericBuild inputs. - + - + The function genericBuild is defined in the file $stdenv/setup. - + - + The final step calls the shell function genericBuild, which performs the steps that @@ -73,9 +71,11 @@ genericBuild bzip2, etc. It can be customised in many ways; see the Nixpkgs manual for details. - + + + - + Discerning readers will note that the buildInputs could just as well have been set in the Nix diff --git a/doc/manual/expressions/language-constructs.xml b/doc/manual/expressions/language-constructs.xml index 0d0cbbe15..4d316609c 100644 --- a/doc/manual/expressions/language-constructs.xml +++ b/doc/manual/expressions/language-constructs.xml @@ -278,7 +278,9 @@ evaluate to a Boolean value. If it evaluates to true, e2 is returned; otherwise expression evaluation is aborted and a backtrace is printed. -Nix expression for Subversion +Here is a Nix expression for the Subversion package that shows +how assertions can be used:. + { localServer ? false , httpServer ? false @@ -290,9 +292,9 @@ otherwise expression evaluation is aborted and a backtrace is printed. , openssl ? null, httpd ? null, db4 ? null, expat, swig ? null, j2sdk ? null }: -assert localServer -> db4 != null; -assert httpServer -> httpd != null && httpd.expat == expat; -assert sslSupport -> openssl != null && (httpServer -> httpd.openssl == openssl); +assert localServer -> db4 != null; ① +assert httpServer -> httpd != null && httpd.expat == expat; ② +assert sslSupport -> openssl != null && (httpServer -> httpd.openssl == openssl); ③ assert pythonBindings -> swig != null && swig.pythonSupport; assert javaSwigBindings -> swig != null && swig.javaSupport; assert javahlBindings -> j2sdk != null; @@ -300,26 +302,24 @@ assert javahlBindings -> j2sdk != null; stdenv.mkDerivation { name = "subversion-1.1.1"; ... - openssl = if sslSupport then openssl else null; + openssl = if sslSupport then openssl else null; ④ ... } - - show how assertions are -used in the Nix expression for Subversion. +The points of interest are: - + - + This assertion states that if Subversion is to have support for local repositories, then Berkeley DB is needed. So if the Subversion function is called with the localServer argument set to true but the db4 argument set to null, then the evaluation fails. - + - + This is a more subtle condition: if Subversion is built with Apache (httpServer) support, then the Expat library (an XML library) used by Subversion should be same as the @@ -327,27 +327,27 @@ used in the Nix expression for Subversion. Subversion code ends up being linked with Apache code, and if the Expat libraries do not match, a build- or runtime link error or incompatibility might occur. - + - + This assertion says that in order for Subversion to have SSL support (so that it can access https URLs), an OpenSSL library must be passed. Additionally, it says that if Apache support is enabled, then Apache's OpenSSL should match Subversion's. (Note that if Apache support is not enabled, we don't care about Apache's OpenSSL.) - + - + The conditional here is not really related to assertions, but is worth pointing out: it ensures that if SSL support is disabled, then the Subversion derivation is not dependent on OpenSSL, even if a non-null value was passed. This prevents an unnecessary rebuild of Subversion if OpenSSL changes. - + - + -- cgit v1.2.3 From ca130b73a02f0fbe1d7ef2007d4cd82565eb5eff Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 14:10:59 +0200 Subject: Get rid of Markdown doesn't have floats so we can't have this. --- doc/manual/expressions/builtins.xml | 119 +++++++++++++++++++----------------- 1 file changed, 62 insertions(+), 57 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/builtins.xml b/doc/manual/expressions/builtins.xml index 478b67ce8..877fd3a1b 100644 --- a/doc/manual/expressions/builtins.xml +++ b/doc/manual/expressions/builtins.xml @@ -434,88 +434,93 @@ stdenv.mkDerivation { … } - - Fetching a private repository over SSH - builtins.fetchGit { + Here are some examples of how to use + fetchGit. + + + + + To fetch a private repository over SSH: + + builtins.fetchGit { url = "git@github.com:my-secret/repository.git"; ref = "master"; rev = "adab8b916a45068c044658c4158d81878f9ed1c3"; } - - - Fetching an arbitrary ref - builtins.fetchGit { + + + + To fetch an arbitrary reference: + + builtins.fetchGit { url = "https://github.com/NixOS/nix.git"; ref = "refs/heads/0.5-release"; } - - - - Fetching a repository's specific commit on an arbitrary branch - - If the revision you're looking for is in the default branch - of the git repository you don't strictly need to specify - the branch name in the ref attribute. - - - However, if the revision you're looking for is in a future - branch for the non-default branch you will need to specify - the the ref attribute as well. - - builtins.fetchGit { + + + + + If the revision you're looking for is in the default branch + of the git repository you don't strictly need to specify + the branch name in the ref attribute. + + + However, if the revision you're looking for is in a future + branch for the non-default branch you will need to specify + the the ref attribute as well. + + + builtins.fetchGit { url = "https://github.com/nixos/nix.git"; rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452"; ref = "1.11-maintenance"; } - + + + + It is nice to always specify the branch which a revision + belongs to. Without the branch being specified, the + fetcher might fail if the default branch changes. + Additionally, it can be confusing to try a commit from a + non-default branch and see the fetch fail. If the branch + is specified the fault is much more obvious. + + + + + - It is nice to always specify the branch which a revision - belongs to. Without the branch being specified, the - fetcher might fail if the default branch changes. - Additionally, it can be confusing to try a commit from a - non-default branch and see the fetch fail. If the branch - is specified the fault is much more obvious. + If the revision you're looking for is in the default branch + of the git repository you may omit the + ref attribute. - - - - - Fetching a repository's specific commit on the default branch - - If the revision you're looking for is in the default branch - of the git repository you may omit the - ref attribute. - - builtins.fetchGit { + builtins.fetchGit { url = "https://github.com/nixos/nix.git"; rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452"; } - + - - Fetching a tag - builtins.fetchGit { + + To fetch a specific tag: + builtins.fetchGit { url = "https://github.com/nixos/nix.git"; ref = "refs/tags/1.9"; } - - - - Fetching the latest version of a remote branch - - builtins.fetchGit can behave impurely - fetch the latest version of a remote branch. - - Nix will refetch the branch in accordance to - . - This behavior is disabled in - Pure evaluation mode. + + + + To fetch the latest version of a remote branch: builtins.fetchGit { url = "ssh://git@github.com/nixos/nix.git"; ref = "master"; } - + Nix will refetch the branch in accordance to + . + This behavior is disabled in Pure + evaluation mode. + + -- cgit v1.2.3 From ee051084723333fc5889c604c829669800e8b43c Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 14:20:54 +0200 Subject: ->
Pandoc silently ignores ... --- doc/manual/expressions/language-constructs.xml | 32 +++++++++++++------------- doc/manual/expressions/language-values.xml | 12 +++++----- 2 files changed, 22 insertions(+), 22 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/language-constructs.xml b/doc/manual/expressions/language-constructs.xml index 4d316609c..82d3afed1 100644 --- a/doc/manual/expressions/language-constructs.xml +++ b/doc/manual/expressions/language-constructs.xml @@ -6,7 +6,7 @@ Language Constructs -Recursive sets +
Recursive sets Recursive sets are just normal sets, but the attributes can refer to each other. For example, @@ -38,10 +38,10 @@ does not terminateActually, Nix detects infinite recursion in this case and aborts (infinite recursion encountered).. - +
-Let-expressions +
Let-expressions A let-expression allows you to define local variables for an expression. For instance, @@ -56,10 +56,10 @@ evaluates to "foobar". - +
-Inheriting attributes +
Inheriting attributes When defining a set or in a let-expression it is often convenient to copy variables from the surrounding lexical scope (e.g., when you want to propagate @@ -129,10 +129,10 @@ a = src-set.a; b = src-set.b; c = src-set.c; when used while defining local variables in a let-expression or while defining a set. - +
-Functions +
Functions Functions have the following form: @@ -248,10 +248,10 @@ in concat { x = "foo"; y = "bar"; } - +
-Conditionals +
Conditionals Conditionals look like this: @@ -262,10 +262,10 @@ where e1 is an expression that should evaluate to a Boolean value (true or false). - +
-Assertions +
Assertions Assertions are generally used to check that certain requirements on or between features and dependencies hold. They look like this: @@ -349,11 +349,11 @@ stdenv.mkDerivation { - +
-With-expressions +
With-expressions A with-expression, @@ -394,16 +394,16 @@ let a = 1; in let a = 2; in let a = 3; in let a = 4; in ... - +
-Comments +
Comments Comments can be single-line, started with a # character, or inline/multi-line, enclosed within /* ... */. - +
diff --git a/doc/manual/expressions/language-values.xml b/doc/manual/expressions/language-values.xml index 4a72c67a8..6c0fcbacb 100644 --- a/doc/manual/expressions/language-values.xml +++ b/doc/manual/expressions/language-values.xml @@ -7,7 +7,7 @@ Values -Simple Values +
Simple Values Nix has the following basic data types: @@ -193,10 +193,10 @@ stdenv.mkDerivation { - +
-Lists +
Lists Lists are formed by enclosing a whitespace-separated list of values between square brackets. For example, @@ -217,10 +217,10 @@ function and the fifth being a set. Note that lists are only lazy in values, and they are strict in length. - +
-Sets +
Sets Sets are really the core of the language, since ultimately the Nix language is all about creating derivations, which are really just @@ -307,7 +307,7 @@ a form of object-oriented programming, for example. - +
-- cgit v1.2.3 From 802150f987e720452920a3d1993c3b4b36861116 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Thu, 23 Jul 2020 14:28:05 +0200 Subject: -> Pandoc doesn't know so let's force it to be rendered as italics. --- doc/manual/expressions/advanced-attributes.xml | 18 +- doc/manual/expressions/build-script.xml | 2 +- doc/manual/expressions/builtins.xml | 420 ++++++++++----------- doc/manual/expressions/expression-syntax.xml | 10 +- doc/manual/expressions/generic-builder.xml | 2 +- doc/manual/expressions/language-constructs.xml | 24 +- doc/manual/expressions/language-operators.xml | 78 ++-- doc/manual/expressions/language-values.xml | 8 +- doc/manual/expressions/simple-building-testing.xml | 2 +- 9 files changed, 282 insertions(+), 282 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/advanced-attributes.xml b/doc/manual/expressions/advanced-attributes.xml index 3a0413ceb..794d020d9 100644 --- a/doc/manual/expressions/advanced-attributes.xml +++ b/doc/manual/expressions/advanced-attributes.xml @@ -91,12 +91,12 @@ disallowedRequisites = [ foobar ]; references graph of their inputs. The attribute is a list of inputs in the Nix store whose references graph the builder needs to know. The value of this attribute should be a list of pairs - [ name1 - path1 name2 - path2 ... + [ name1 + path1 name2 + path2 ... ]. The references graph of each - pathN will be stored in a text file - nameN in the temporary build directory. + pathN will be stored in a text file + nameN in the temporary build directory. The text files have the format used by nix-store --register-validity (with the deriver fields left empty). For example, when the following derivation is built: @@ -135,7 +135,7 @@ derivation { Nixpkgs has the line -impureEnvVars = [ "http_proxy" "https_proxy" ... ]; +impureEnvVars = [ "http_proxy" "https_proxy" ... ]; to make it use the proxy server configuration specified by the @@ -297,11 +297,11 @@ big = "a very long string"; bigPath will contain the absolute path to a temporary file containing a very long string. That is, for any attribute - x listed in + x listed in passAsFile, Nix will pass an environment - variable xPath holding + variable xPath holding the path of the file containing the value of attribute - x. This is useful when you need to pass + x. This is useful when you need to pass large strings to a builder, since most operating systems impose a limit on the size of the environment (typically, a few hundred kilobyte). diff --git a/doc/manual/expressions/build-script.xml b/doc/manual/expressions/build-script.xml index 892274f50..c9af198f2 100644 --- a/doc/manual/expressions/build-script.xml +++ b/doc/manual/expressions/build-script.xml @@ -58,7 +58,7 @@ steps: the PATH. The perl environment variable points to the location of the Perl package (since it was passed in as an attribute to the derivation), so - $perl/bin is the + $perl/bin is the directory containing the Perl interpreter. diff --git a/doc/manual/expressions/builtins.xml b/doc/manual/expressions/builtins.xml index 877fd3a1b..4ad481ad3 100644 --- a/doc/manual/expressions/builtins.xml +++ b/doc/manual/expressions/builtins.xml @@ -22,34 +22,34 @@ available as builtins.derivation. - abort s - builtins.abort s + abort s + builtins.abort s Abort Nix expression evaluation, print error - message s. + message s. builtins.add - e1 e2 + e1 e2 Return the sum of the numbers - e1 and - e2. + e1 and + e2. builtins.all - pred list + pred list Return true if the function - pred returns true - for all elements of list, + pred returns true + for all elements of list, and false otherwise. @@ -57,11 +57,11 @@ available as builtins.derivation. builtins.any - pred list + pred list Return true if the function - pred returns true - for at least one element of list, + pred returns true + for at least one element of list, and false otherwise. @@ -69,10 +69,10 @@ available as builtins.derivation. builtins.attrNames - set + set Return the names of the attributes in the set - set in an alphabetically sorted list. For instance, + set in an alphabetically sorted list. For instance, builtins.attrNames { y = 1; x = "foo"; } evaluates to [ "x" "y" ]. @@ -81,20 +81,20 @@ available as builtins.derivation. builtins.attrValues - set + set Return the values of the attributes in the set - set in the order corresponding to the + set in the order corresponding to the sorted attribute names. - baseNameOf s + baseNameOf s Return the base name of the - string s, that is, everything following + string s, that is, everything following the final slash in the string. This is similar to the GNU basename command. @@ -103,33 +103,33 @@ available as builtins.derivation. builtins.bitAnd - e1 e2 + e1 e2 Return the bitwise AND of the integers - e1 and - e2. + e1 and + e2. builtins.bitOr - e1 e2 + e1 e2 Return the bitwise OR of the integers - e1 and - e2. + e1 and + e2. builtins.bitXor - e1 e2 + e1 e2 Return the bitwise XOR of the integers - e1 and - e2. + e1 and + e2. @@ -154,15 +154,15 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.compareVersions - s1 s2 + s1 s2 Compare two strings representing versions and return -1 if version - s1 is older than version - s2, 0 if they are + s1 is older than version + s2, 0 if they are the same, and 1 if - s1 is newer than - s2. The version comparison algorithm + s1 is newer than + s2. The version comparison algorithm is the same as the one used by nix-env -u. @@ -172,7 +172,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.concatLists - lists + lists Concatenate a list of lists into a single list. @@ -181,7 +181,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.concatStringsSep - separator list + separator list Concatenate a list of strings with a separator between each element, e.g. concatStringsSep "/" @@ -225,12 +225,12 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.deepSeq - e1 e2 + e1 e2 This is like seq - e1 - e2, except that - e1 is evaluated + e1 + e2, except that + e1 is evaluated deeply: if it’s a list or set, its elements or attributes are also evaluated recursively. @@ -239,9 +239,9 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" derivation - attrs + attrs builtins.derivation - attrs + attrs derivation is described in . @@ -250,11 +250,11 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" - dirOf s - builtins.dirOf s + dirOf s + builtins.dirOf s Return the directory part of the string - s, that is, everything before the final + s, that is, everything before the final slash in the string. This is similar to the GNU dirname command. @@ -263,21 +263,21 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.div - e1 e2 + e1 e2 Return the quotient of the numbers - e1 and - e2. + e1 and + e2. builtins.elem - x xs + x xs Return true if a value equal to - x occurs in the list - xs, and false + x occurs in the list + xs, and false otherwise. @@ -285,10 +285,10 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.elemAt - xs n + xs n - Return element n from - the list xs. Elements are counted + Return element n from + the list xs. Elements are counted starting from 0. A fatal error occurs if the index is out of bounds. @@ -297,7 +297,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else "" builtins.fetchurl - url + url Download the specified URL and return the path of the downloaded file. This function is not available if fetchTarball - url + url builtins.fetchTarball - url + url Download the specified URL, unpack it and return the path of the unpacked tree. The file must be a tape archive @@ -333,9 +333,9 @@ stdenv.mkDerivation { … } The fetched tarball is cached for a certain amount of time (1 hour by default) in ~/.cache/nix/tarballs/. You can change the cache timeout either on the command line with - or + or in the Nix configuration file with this option: - number of seconds to cache. + number of seconds to cache. Note that when obtaining the hash with nix-prefetch-url @@ -367,12 +367,12 @@ stdenv.mkDerivation { … } builtins.fetchGit - args + args - Fetch a path from git. args can be + Fetch a path from git. args can be a URL, in which case the HEAD of the repo at that URL is fetched. Otherwise, it can be an attribute with the following attributes (all except url optional): @@ -526,11 +526,11 @@ stdenv.mkDerivation { … } builtins.filter - f xs + f xs Return a list consisting of the elements of - xs for which the function - f returns + xs for which the function + f returns true. @@ -538,7 +538,7 @@ stdenv.mkDerivation { … } builtins.filterSource - e1 e2 + e1 e2 @@ -569,10 +569,10 @@ stdenv.mkDerivation { - Thus, the first argument e1 + Thus, the first argument e1 must be a predicate function that is called for each regular file, directory or symlink in the source tree - e2. If the function returns + e2. If the function returns true, the file is copied to the Nix store, otherwise it is omitted. The function is called with two arguments. The first is the full path of the file. The second @@ -584,7 +584,7 @@ stdenv.mkDerivation { the Nix store, so if the predicate returns true for them, the copy will fail). If you exclude a directory, the entire corresponding subtree of - e2 will be excluded. + e2 will be excluded. @@ -593,7 +593,7 @@ stdenv.mkDerivation { builtins.foldl’ - op nul list + op nul list Reduce a list by applying a binary operator, from left to right, e.g. foldl’ op nul [x0 x1 x2 ...] = op (op @@ -607,11 +607,11 @@ stdenv.mkDerivation { builtins.functionArgs - f + f Return a set containing the names of the formal arguments expected - by the function f. + by the function f. The value of each attribute is a Boolean denoting whether the corresponding argument has a default value. For instance, functionArgs ({ x, y ? 123}: ...) = { x = false; y = true; }. @@ -625,7 +625,7 @@ stdenv.mkDerivation { - builtins.fromJSON e + builtins.fromJSON e Convert a JSON string to a Nix value. For example, @@ -642,12 +642,12 @@ builtins.fromJSON ''{"x": [1, 2, 3], "y": null}'' builtins.genList - generator length + generator length Generate list of size - length, with each element - i equal to the value returned by - generator i. For + length, with each element + i equal to the value returned by + generator i. For example, @@ -661,13 +661,13 @@ builtins.genList (x: x * x) 5 builtins.getAttr - s set + s set getAttr returns the attribute - named s from - set. Evaluation aborts if the + named s from + set. Evaluation aborts if the attribute doesn’t exist. This is a dynamic version of the - . operator, since s + . operator, since s is an expression rather than an identifier. @@ -675,10 +675,10 @@ builtins.genList (x: x * x) 5 builtins.getEnv - s + s getEnv returns the value of - the environment variable s, or an empty + the environment variable s, or an empty string if the variable doesn’t exist. This function should be used with care, as it can introduce all sorts of nasty environment dependencies in your Nix expression. @@ -694,14 +694,14 @@ builtins.genList (x: x * x) 5 builtins.hasAttr - s set + s set hasAttr returns - true if set has an - attribute named s, and + true if set has an + attribute named s, and false otherwise. This is a dynamic version of the ? operator, since - s is an expression rather than an + s is an expression rather than an identifier. @@ -709,11 +709,11 @@ builtins.genList (x: x * x) 5 builtins.hashString - type s + type s Return a base-16 representation of the - cryptographic hash of string s. The - hash algorithm specified by type must + cryptographic hash of string s. The + hash algorithm specified by type must be one of "md5", "sha1", "sha256" or "sha512". @@ -722,11 +722,11 @@ builtins.genList (x: x * x) 5 builtins.hashFile - type p + type p Return a base-16 representation of the - cryptographic hash of the file at path p. The - hash algorithm specified by type must + cryptographic hash of the file at path p. The + hash algorithm specified by type must be one of "md5", "sha1", "sha256" or "sha512". @@ -735,7 +735,7 @@ builtins.genList (x: x * x) 5 builtins.head - list + list Return the first element of a list; abort evaluation if the argument isn’t a list or is an empty list. You @@ -747,13 +747,13 @@ builtins.genList (x: x * x) 5 import - path + path builtins.import - path + path Load, parse and return the Nix expression in the - file path. If path - is a directory, the file default.nix + file path. If path + is a directory, the file default.nix in that directory is loaded. Evaluation aborts if the file doesn’t exist or contains an incorrect Nix expression. import implements Nix’s module system: you @@ -763,7 +763,7 @@ builtins.genList (x: x * x) 5 Unlike some languages, import is a regular function in Nix. Paths using the angle bracket syntax (e.g., - import <foo>) are normal path + import <foo>) are normal path values (see ). A Nix expression loaded by import must @@ -810,21 +810,21 @@ x: x + 456 builtins.intersectAttrs - e1 e2 + e1 e2 Return a set consisting of the attributes in the - set e2 that also exist in the set - e1. + set e2 that also exist in the set + e1. builtins.isAttrs - e + e Return true if - e evaluates to a set, and + e evaluates to a set, and false otherwise. @@ -832,20 +832,20 @@ x: x + 456 builtins.isList - e + e Return true if - e evaluates to a list, and + e evaluates to a list, and false otherwise. builtins.isFunction - e + e Return true if - e evaluates to a function, and + e evaluates to a function, and false otherwise. @@ -853,10 +853,10 @@ x: x + 456 builtins.isString - e + e Return true if - e evaluates to a string, and + e evaluates to a string, and false otherwise. @@ -864,10 +864,10 @@ x: x + 456 builtins.isInt - e + e Return true if - e evaluates to an int, and + e evaluates to an int, and false otherwise. @@ -875,10 +875,10 @@ x: x + 456 builtins.isFloat - e + e Return true if - e evaluates to a float, and + e evaluates to a float, and false otherwise. @@ -886,31 +886,31 @@ x: x + 456 builtins.isBool - e + e Return true if - e evaluates to a bool, and + e evaluates to a bool, and false otherwise. builtins.isPath - e + e Return true if - e evaluates to a path, and + e evaluates to a path, and false otherwise. isNull - e + e builtins.isNull - e + e Return true if - e evaluates to null, + e evaluates to null, and false otherwise. This function is deprecated; @@ -923,23 +923,23 @@ x: x + 456 builtins.length - e + e Return the length of the list - e. + e. builtins.lessThan - e1 e2 + e1 e2 Return true if the number - e1 is less than the number - e2, and false + e1 is less than the number + e2, and false otherwise. Evaluation aborts if either - e1 or e2 + e1 or e2 does not evaluate to a number. @@ -947,7 +947,7 @@ x: x + 456 builtins.listToAttrs - e + e Construct a set from a list specifying the names and values of each attribute. Each element of the list should be @@ -975,12 +975,12 @@ builtins.listToAttrs map - f list + f list builtins.map - f list + f list - Apply the function f to - each element in the list list. For + Apply the function f to + each element in the list list. For example, @@ -994,12 +994,12 @@ map (x: "foo" + x) [ "bar" "bla" "abc" ] builtins.match - regex str + regex str Returns a list if the extended - POSIX regular expression regex - matches str precisely, otherwise returns + POSIX regular expression regex + matches str precisely, otherwise returns null. Each item in the list is a regex group. @@ -1031,20 +1031,20 @@ Evaluates to [ "foo" ]. builtins.mul - e1 e2 + e1 e2 Return the product of the numbers - e1 and - e2. + e1 and + e2. builtins.parseDrvName - s + s - Split the string s into + Split the string s into a package name and version. The package name is everything up to but not including the first dash followed by a digit, and the version is everything following that dash. The result is returned @@ -1058,13 +1058,13 @@ Evaluates to [ "foo" ]. builtins.path - args + args An enrichment of the built-in path type, based on the attributes - present in args. All are optional + present in args. All are optional except path: @@ -1127,20 +1127,20 @@ Evaluates to [ "foo" ]. builtins.pathExists - path + path Return true if the path - path exists at evaluation time, and + path exists at evaluation time, and false otherwise. builtins.placeholder - output + output Return a placeholder string for the specified - output that will be substituted by the + output that will be substituted by the corresponding output path at build time. Typical outputs would be "out", "bin" or "dev". @@ -1148,10 +1148,10 @@ Evaluates to [ "foo" ]. builtins.readDir - path + path Return the contents of the directory - path as a set mapping directory entries + path as a set mapping directory entries to the corresponding file type. For instance, if directory A contains a regular file B and another directory @@ -1171,24 +1171,24 @@ Evaluates to [ "foo" ]. builtins.readFile - path + path Return the contents of the file - path as a string. + path as a string. removeAttrs - set list + set list builtins.removeAttrs - set list + set list Remove the attributes listed in - list from - set. The attributes don’t have to - exist in set. For instance, + list from + set. The attributes don’t have to + exist in set. For instance, removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ] @@ -1200,12 +1200,12 @@ removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ] builtins.replaceStrings - from to s + from to s - Given string s, replace - every occurrence of the strings in from + Given string s, replace + every occurrence of the strings in from with the corresponding string in - to. For example, + to. For example, builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar" @@ -1218,23 +1218,23 @@ builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar" builtins.seq - e1 e2 + e1 e2 - Evaluate e1, then - evaluate and return e2. This ensures + Evaluate e1, then + evaluate and return e2. This ensures that a computation is strict in the value of - e1. + e1. builtins.sort - comparator list + comparator list - Return list in sorted + Return list in sorted order. It repeatedly calls the function - comparator with two elements. The + comparator with two elements. The comparator should return true if the first element is less than the second, and false otherwise. For example, @@ -1254,13 +1254,13 @@ builtins.sort builtins.lessThan [ 483 249 526 147 42 77 ] builtins.split - regex str + regex str Returns a list composed of non matched strings interleaved with the lists of the extended - POSIX regular expression regex matches - of str. Each item in the lists of matched + POSIX regular expression regex matches + of str. Each item in the lists of matched sequences is a regex group. @@ -1293,7 +1293,7 @@ Evaluates to [ " " [ "FOO" ] " " ]. builtins.splitVersion - s + s Split a string representing a version into its components, by the same version splitting logic underlying the @@ -1305,10 +1305,10 @@ Evaluates to [ " " [ "FOO" ] " " ]. builtins.stringLength - e + e Return the length of the string - e. If e is + e. If e is not a string, evaluation is aborted. @@ -1316,29 +1316,29 @@ Evaluates to [ " " [ "FOO" ] " " ]. builtins.sub - e1 e2 + e1 e2 Return the difference between the numbers - e1 and - e2. + e1 and + e2. builtins.substring - start len - s + start len + s Return the substring of - s from character position - start (zero-based) up to but not - including start + len. If - start is greater than the length of the - string, an empty string is returned, and if start + - len lies beyond the end of the string, only the + s from character position + start (zero-based) up to but not + including start + len. If + start is greater than the length of the + string, an empty string is returned, and if start + + len lies beyond the end of the string, only the substring up to the end of the string is returned. - start must be + start must be non-negative. For example, @@ -1353,7 +1353,7 @@ builtins.substring 0 3 "nixos" builtins.tail - list + list Return the second to last elements of a list; abort evaluation if the argument isn’t a list or is an empty @@ -1364,12 +1364,12 @@ builtins.substring 0 3 "nixos" throw - s + s builtins.throw - s + s Throw an error message - s. This usually aborts Nix expression + s. This usually aborts Nix expression evaluation, but in nix-env -qa and other commands that try to evaluate a set of derivations to get information about those derivations, a derivation that throws an @@ -1381,12 +1381,12 @@ builtins.substring 0 3 "nixos" builtins.toFile - name - s + name + s - Store the string s in a + Store the string s in a file in the Nix store and return its path. The file has suffix - name. This file can be used as an + name. This file can be used as an input to derivations. One application is to write builders “inline”. For instance, the following Nix expression combines and ... + ... "; in builtins.toFile "builder.sh" " source $stdenv/setup - ... + ... cp ${configFile} $out/etc/foo.conf "; @@ -1459,10 +1459,10 @@ in foo - builtins.toJSON e + builtins.toJSON e Return a string containing a JSON representation - of e. Strings, integers, floats, booleans, + of e. Strings, integers, floats, booleans, nulls and lists are mapped to their JSON equivalents. Sets (except derivations) are represented as objects. Derivations are translated to a JSON string containing the derivation’s output @@ -1473,7 +1473,7 @@ in foo - builtins.toPath s + builtins.toPath s DEPRECATED. Use /. + "/path" to convert a string into an absolute path. For relative paths, @@ -1484,12 +1484,12 @@ in foo - toString e - builtins.toString e + toString e + builtins.toString e Convert the expression - e to a string. - e can be: + e to a string. + e can be: A string (in which case the string is returned unmodified). A path (e.g., toString /foo/bar yields "/foo/bar". @@ -1505,10 +1505,10 @@ in foo - builtins.toXML e + builtins.toXML e Return a string containing an XML representation - of e. The main application for + of e. The main application for toXML is to communicate information with the builder in a more structured format than plain environment variables. @@ -1612,26 +1612,26 @@ stdenv.mkDerivation (rec { builtins.trace - e1 e2 + e1 e2 - Evaluate e1 and print its + Evaluate e1 and print its abstract syntax representation on standard error. Then return - e2. This function is useful for + e2. This function is useful for debugging. builtins.tryEval - e + e - Try to shallowly evaluate e. + Try to shallowly evaluate e. Return a set containing the attributes success - (true if e evaluated + (true if e evaluated successfully, false if an error was thrown) and - value, equalling e + value, equalling e if successful and false otherwise. Note that this - doesn't evaluate e deeply, so + doesn't evaluate e deeply, so let e = { x = throw ""; }; in (builtins.tryEval e).success will be true. Using builtins.deepSeq one can get the expected result: let e = { x = throw ""; @@ -1644,10 +1644,10 @@ stdenv.mkDerivation (rec { builtins.typeOf - e + e Return a string representing the type of the value - e, namely "int", + e, namely "int", "bool", "string", "path", "null", "set", "list", diff --git a/doc/manual/expressions/expression-syntax.xml b/doc/manual/expressions/expression-syntax.xml index 562a9e9f4..853e40b58 100644 --- a/doc/manual/expressions/expression-syntax.xml +++ b/doc/manual/expressions/expression-syntax.xml @@ -50,7 +50,7 @@ the single Nix expression in that directory Nix functions generally have the form { x, y, ..., z }: e where x, y, etc. are the names of the expected arguments, and where - e is the body of the function. So + e is the body of the function. So here, the entire remainder of the file is the body of the function; when given the required arguments, the body should describe how to build an instance of the Hello package. @@ -69,10 +69,10 @@ the single Nix expression in that directory attributes. A set is just a list of key/value pairs where each key is a string and each value is an arbitrary Nix expression. They take the general form { - name1 = - expr1; ... - nameN = - exprN; }. + name1 = + expr1; ... + nameN = + exprN; }. diff --git a/doc/manual/expressions/generic-builder.xml b/doc/manual/expressions/generic-builder.xml index 71b342f99..f6e67813d 100644 --- a/doc/manual/expressions/generic-builder.xml +++ b/doc/manual/expressions/generic-builder.xml @@ -44,7 +44,7 @@ genericBuild ③ subdirectory, it's added to GCC's header search path; and so on.How does it work? setup tries to source the file - pkg/nix-support/setup-hook + pkg/nix-support/setup-hook of all dependencies. These “setup hooks” can then set up whatever environment variables they want; for instance, the setup hook for Perl sets the PERL5LIB environment variable to diff --git a/doc/manual/expressions/language-constructs.xml b/doc/manual/expressions/language-constructs.xml index 82d3afed1..86c25d723 100644 --- a/doc/manual/expressions/language-constructs.xml +++ b/doc/manual/expressions/language-constructs.xml @@ -137,7 +137,7 @@ while defining a set. Functions have the following form: -pattern: body +pattern: body The pattern specifies what the argument of the function must look like, and binds variables in the body to (parts of) the @@ -190,9 +190,9 @@ map (concat "foo") [ "bar" "bla" "abc" ] It is possible to provide default values for attributes, in which case they are allowed to be missing. A default value is specified by writing - name ? - e, where - e is an arbitrary expression. For example, + name ? + e, where + e is an arbitrary expression. For example, { x, y ? "foo", z ? "bar" }: z + y + x @@ -256,9 +256,9 @@ in concat { x = "foo"; y = "bar"; } Conditionals look like this: -if e1 then e2 else e3 +if e1 then e2 else e3 -where e1 is an expression that should +where e1 is an expression that should evaluate to a Boolean value (true or false). @@ -271,11 +271,11 @@ evaluate to a Boolean value (true or on or between features and dependencies hold. They look like this: -assert e1; e2 +assert e1; e2 -where e1 is an expression that should +where e1 is an expression that should evaluate to a Boolean value. If it evaluates to -true, e2 is returned; +true, e2 is returned; otherwise expression evaluation is aborted and a backtrace is printed. Here is a Nix expression for the Subversion package that shows @@ -358,10 +358,10 @@ stdenv.mkDerivation { A with-expression, -with e1; e2 +with e1; e2 -introduces the set e1 into the lexical -scope of the expression e2. For instance, +introduces the set e1 into the lexical +scope of the expression e2. For instance, let as = { x = "foo"; y = "bar"; }; diff --git a/doc/manual/expressions/language-operators.xml b/doc/manual/expressions/language-operators.xml index 4f11bf529..7f69bfcef 100644 --- a/doc/manual/expressions/language-operators.xml +++ b/doc/manual/expressions/language-operators.xml @@ -25,48 +25,48 @@ weakest binding). Select - e . - attrpath - [ or def ] + e . + attrpath + [ or def ] none Select attribute denoted by the attribute path - attrpath from set - e. (An attribute path is a + attrpath from set + e. (An attribute path is a dot-separated list of attribute names.) If the attribute - doesn’t exist, return def if + doesn’t exist, return def if provided, otherwise abort evaluation. 1 Application - e1 e2 + e1 e2 left - Call function e1 with - argument e2. + Call function e1 with + argument e2. 2 Arithmetic Negation - - e + - e none Arithmetic negation. 3 Has Attribute - e ? - attrpath + e ? + attrpath none - Test whether set e contains - the attribute denoted by attrpath; + Test whether set e contains + the attribute denoted by attrpath; return true or false. 4 List Concatenation - e1 ++ e2 + e1 ++ e2 right List concatenation. 5 @@ -74,7 +74,7 @@ weakest binding). Multiplication - e1 * e2, + e1 * e2, left Arithmetic multiplication. @@ -83,7 +83,7 @@ weakest binding). Division - e1 / e2 + e1 / e2 left Arithmetic division. @@ -92,7 +92,7 @@ weakest binding). Addition - e1 + e2 + e1 + e2 left Arithmetic addition. @@ -101,7 +101,7 @@ weakest binding). Subtraction - e1 - e2 + e1 - e2 left Arithmetic subtraction. @@ -110,7 +110,7 @@ weakest binding). String Concatenation - string1 + string2 + string1 + string2 left String concatenation. @@ -118,19 +118,19 @@ weakest binding). Not - ! e + ! e none Boolean negation. 8 Update - e1 // - e2 + e1 // + e2 right Return a set consisting of the attributes in - e1 and - e2 (with the latter taking + e1 and + e2 (with the latter taking precedence over the former in case of equally named attributes). 9 @@ -138,7 +138,7 @@ weakest binding). Less Than - e1 < e2, + e1 < e2, none Arithmetic comparison. @@ -147,7 +147,7 @@ weakest binding). Less Than or Equal To - e1 <= e2 + e1 <= e2 none Arithmetic comparison. @@ -156,7 +156,7 @@ weakest binding). Greater Than - e1 > e2 + e1 > e2 none Arithmetic comparison. @@ -165,7 +165,7 @@ weakest binding). Greater Than or Equal To - e1 >= e2 + e1 >= e2 none Arithmetic comparison. @@ -174,7 +174,7 @@ weakest binding). Equality - e1 == e2 + e1 == e2 none Equality. @@ -183,7 +183,7 @@ weakest binding). Inequality - e1 != e2 + e1 != e2 none Inequality. @@ -191,28 +191,28 @@ weakest binding). Logical AND - e1 && - e2 + e1 && + e2 left Logical AND. 12 Logical OR - e1 || - e2 + e1 || + e2 left Logical OR. 13 Logical Implication - e1 -> - e2 + e1 -> + e2 none Logical implication (equivalent to - !e1 || - e2). + !e1 || + e2). 14 diff --git a/doc/manual/expressions/language-values.xml b/doc/manual/expressions/language-values.xml index 6c0fcbacb..cebafb1f5 100644 --- a/doc/manual/expressions/language-values.xml +++ b/doc/manual/expressions/language-values.xml @@ -30,7 +30,7 @@ You can include the result of an expression into a string by enclosing it in - ${...}, a feature + ${...}, a feature known as antiquotation. The enclosed expression must evaluate to something that can be coerced into a string (meaning that it must be a string, a path, or a @@ -93,7 +93,7 @@ configureFlags = " text on the initial line. Antiquotation - (${expr}) is + (${expr}) is supported in indented strings. Since ${ and '' have @@ -119,7 +119,7 @@ configureFlags = " stdenv.mkDerivation { - ... + ... postInstall = '' mkdir $out/bin $out/etc @@ -127,7 +127,7 @@ stdenv.mkDerivation { echo "Hello World" > $out/etc/foo.conf ${if enableBar then "cp bar $out/bin" else ""} ''; - ... + ... } diff --git a/doc/manual/expressions/simple-building-testing.xml b/doc/manual/expressions/simple-building-testing.xml index 33a802e83..f82223df9 100644 --- a/doc/manual/expressions/simple-building-testing.xml +++ b/doc/manual/expressions/simple-building-testing.xml @@ -19,7 +19,7 @@ building path `/nix/store/632d2b22514d...-hello-2.1.1' hello-2.1.1/ hello-2.1.1/intl/ hello-2.1.1/intl/ChangeLog -... +... $ ls -l result lrwxrwxrwx ... 2006-09-29 10:43 result -> /nix/store/632d2b22514d...-hello-2.1.1 -- cgit v1.2.3 From 8d0b311a1ccd0aef49c6f272aad4ecb5105b285a Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 24 Jul 2020 11:43:44 +0200 Subject: Get rid of footnotes Markdown doesn't support them. --- doc/manual/expressions/build-script.xml | 11 ++++------- doc/manual/expressions/derivations.xml | 19 +++++++++---------- doc/manual/expressions/generic-builder.xml | 6 +++--- doc/manual/expressions/language-constructs.xml | 7 +++---- doc/manual/expressions/language-values.xml | 11 +++++------ doc/manual/expressions/simple-expression.xml | 7 +++---- 6 files changed, 27 insertions(+), 34 deletions(-) (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/build-script.xml b/doc/manual/expressions/build-script.xml index c9af198f2..5c55954fc 100644 --- a/doc/manual/expressions/build-script.xml +++ b/doc/manual/expressions/build-script.xml @@ -33,13 +33,10 @@ steps: When Nix runs a builder, it initially completely clears the environment (except for the attributes declared in the - derivation). For instance, the PATH variable is - emptyActually, it's initialised to - /path-not-set to prevent Bash from setting it - to a default value.. This is done to prevent - undeclared inputs from being used in the build process. If for - example the PATH contained - /usr/bin, then you might accidentally use + derivation). This is done to prevent undeclared inputs from being + used in the build process. If for example the + PATH contained /usr/bin, + then you might accidentally use /usr/bin/gcc. So the first step is to set up the environment. This is diff --git a/doc/manual/expressions/derivations.xml b/doc/manual/expressions/derivations.xml index a11de0088..0625bcdfe 100644 --- a/doc/manual/expressions/derivations.xml +++ b/doc/manual/expressions/derivations.xml @@ -13,16 +13,15 @@ of which specify the inputs of the build. - There must be an attribute named - system whose value must be a string specifying a - Nix platform identifier, such as "i686-linux" or - "x86_64-darwin"To figure out - your platform identifier, look at the line Checking for the - canonical Nix system name in the output of Nix's - configure script. The build - can only be performed on a machine and operating system matching the - platform identifier. (Nix can automatically forward builds for - other platforms by forwarding them to other machines; see There must be an attribute + named system whose value must be a string + specifying a Nix system type, such as + "i686-linux" or + "x86_64-darwin". (To figure out your system type, + run nix -vv --version.) The build can only be + performed on a machine and operating system matching the system + type. (Nix can automatically forward builds for other platforms by + forwarding them to other machines; see .) There must be an attribute named diff --git a/doc/manual/expressions/generic-builder.xml b/doc/manual/expressions/generic-builder.xml index f6e67813d..a6f258abc 100644 --- a/doc/manual/expressions/generic-builder.xml +++ b/doc/manual/expressions/generic-builder.xml @@ -42,14 +42,14 @@ genericBuild ③ bin subdirectory, it's added to PATH; if it has a include subdirectory, it's added to GCC's header search path; and so - on.How does it work? setup - tries to source the file + on. (This is implemented in a modular way: + setup tries to source the file pkg/nix-support/setup-hook of all dependencies. These “setup hooks” can then set up whatever environment variables they want; for instance, the setup hook for Perl sets the PERL5LIB environment variable to contain the lib/site_perl directories of all - inputs. + inputs.) diff --git a/doc/manual/expressions/language-constructs.xml b/doc/manual/expressions/language-constructs.xml index 86c25d723..e1c589f61 100644 --- a/doc/manual/expressions/language-constructs.xml +++ b/doc/manual/expressions/language-constructs.xml @@ -26,7 +26,7 @@ is, in a normal (non-recursive) set, attributes are not added to the lexical scope; in a recursive set, they are. Recursive sets of course introduce the danger of infinite -recursion. For example, +recursion. For example, the expression rec { @@ -34,9 +34,8 @@ rec { y = x; }.x -does not terminateActually, Nix detects infinite -recursion in this case and aborts (infinite recursion -encountered).. +will crash with an infinite recursion encountered +error message. diff --git a/doc/manual/expressions/language-values.xml b/doc/manual/expressions/language-values.xml index cebafb1f5..5520a4938 100644 --- a/doc/manual/expressions/language-values.xml +++ b/doc/manual/expressions/language-values.xml @@ -154,11 +154,10 @@ stdenv.mkDerivation { Paths, e.g., /bin/sh or ./builder.sh. - A path must contain at least one slash to be recognised as such; for - instance, builder.sh is not a - pathIt's parsed as an expression that selects the - attribute sh from the variable - builder.. If the file name is + A path must contain at least one slash to be recognised as such. For + instance, builder.sh is not a path: it's parsed + as an expression that selects the attribute sh + from the variable builder. If the file name is relative, i.e., if it does not begin with a slash, it is made absolute at parse time relative to the directory of the Nix expression that contained it. For instance, if a Nix expression in @@ -176,7 +175,7 @@ stdenv.mkDerivation { Paths can also be specified between angle brackets, e.g. <nixpkgs>. This means that the directories listed in the environment variable - NIX_PATH will be searched + NIX_PATH will be searched for the given file or directory name. diff --git a/doc/manual/expressions/simple-expression.xml b/doc/manual/expressions/simple-expression.xml index 29fd872ee..ad97220a8 100644 --- a/doc/manual/expressions/simple-expression.xml +++ b/doc/manual/expressions/simple-expression.xml @@ -21,10 +21,9 @@ need to do three things: such as dependencies, sources, and so on. Write a builder. This is a - shell scriptIn fact, it can be written in any - language, but typically it's a bash shell - script. that actually builds the package from - the inputs. + shell script that builds the package from the inputs. (In fact, it + can be written in any language, but typically it's a + bash shell script.) Add the package to the file pkgs/top-level/all-packages.nix. The Nix -- cgit v1.2.3 From 1308c8404e19aacc6458b3813d445857620a60a8 Mon Sep 17 00:00:00 2001 From: Eelco Dolstra Date: Fri, 24 Jul 2020 15:48:40 +0200 Subject: Remove DocBook manual --- doc/manual/expressions/advanced-attributes.xml | 351 ----- doc/manual/expressions/arguments-variables.xml | 114 -- doc/manual/expressions/build-script.xml | 114 -- doc/manual/expressions/builtins.xml | 1663 -------------------- doc/manual/expressions/derivations.xml | 210 --- doc/manual/expressions/expression-language.xml | 30 - doc/manual/expressions/expression-syntax.xml | 146 -- doc/manual/expressions/generic-builder.xml | 98 -- doc/manual/expressions/language-constructs.xml | 408 ----- doc/manual/expressions/language-operators.xml | 222 --- doc/manual/expressions/language-values.xml | 312 ---- doc/manual/expressions/simple-building-testing.xml | 76 - doc/manual/expressions/simple-expression.xml | 46 - doc/manual/expressions/writing-nix-expressions.xml | 26 - 14 files changed, 3816 deletions(-) delete mode 100644 doc/manual/expressions/advanced-attributes.xml delete mode 100644 doc/manual/expressions/arguments-variables.xml delete mode 100644 doc/manual/expressions/build-script.xml delete mode 100644 doc/manual/expressions/builtins.xml delete mode 100644 doc/manual/expressions/derivations.xml delete mode 100644 doc/manual/expressions/expression-language.xml delete mode 100644 doc/manual/expressions/expression-syntax.xml delete mode 100644 doc/manual/expressions/generic-builder.xml delete mode 100644 doc/manual/expressions/language-constructs.xml delete mode 100644 doc/manual/expressions/language-operators.xml delete mode 100644 doc/manual/expressions/language-values.xml delete mode 100644 doc/manual/expressions/simple-building-testing.xml delete mode 100644 doc/manual/expressions/simple-expression.xml delete mode 100644 doc/manual/expressions/writing-nix-expressions.xml (limited to 'doc/manual/expressions') diff --git a/doc/manual/expressions/advanced-attributes.xml b/doc/manual/expressions/advanced-attributes.xml deleted file mode 100644 index 794d020d9..000000000 --- a/doc/manual/expressions/advanced-attributes.xml +++ /dev/null @@ -1,351 +0,0 @@ -
- -Advanced Attributes - -Derivations can declare some infrequently used optional -attributes. - - - - allowedReferences - - The optional attribute - allowedReferences specifies a list of legal - references (dependencies) of the output of the builder. For - example, - - -allowedReferences = []; - - - enforces that the output of a derivation cannot have any runtime - dependencies on its inputs. To allow an output to have a runtime - dependency on itself, use "out" as a list item. - This is used in NixOS to check that generated files such as - initial ramdisks for booting Linux don’t have accidental - dependencies on other paths in the Nix store. - - - - - allowedRequisites - - This attribute is similar to - allowedReferences, but it specifies the legal - requisites of the whole closure, so all the dependencies - recursively. For example, - - -allowedRequisites = [ foobar ]; - - - enforces that the output of a derivation cannot have any other - runtime dependency than foobar, and in addition - it enforces that foobar itself doesn't - introduce any other dependency itself. - - - - disallowedReferences - - The optional attribute - disallowedReferences specifies a list of illegal - references (dependencies) of the output of the builder. For - example, - - -disallowedReferences = [ foo ]; - - - enforces that the output of a derivation cannot have a direct runtime - dependencies on the derivation foo. - - - - - disallowedRequisites - - This attribute is similar to - disallowedReferences, but it specifies illegal - requisites for the whole closure, so all the dependencies - recursively. For example, - - -disallowedRequisites = [ foobar ]; - - - enforces that the output of a derivation cannot have any - runtime dependency on foobar or any other derivation - depending recursively on foobar. - - - - - exportReferencesGraph - - This attribute allows builders access to the - references graph of their inputs. The attribute is a list of - inputs in the Nix store whose references graph the builder needs - to know. The value of this attribute should be a list of pairs - [ name1 - path1 name2 - path2 ... - ]. The references graph of each - pathN will be stored in a text file - nameN in the temporary build directory. - The text files have the format used by nix-store - --register-validity (with the deriver fields left - empty). For example, when the following derivation is built: - - -derivation { - ... - exportReferencesGraph = [ "libfoo-graph" libfoo ]; -}; - - - the references graph of libfoo is placed in the - file libfoo-graph in the temporary build - directory. - - exportReferencesGraph is useful for - builders that want to do something with the closure of a store - path. Examples include the builders in NixOS that generate the - initial ramdisk for booting Linux (a cpio - archive containing the closure of the boot script) and the - ISO-9660 image for the installation CD (which is populated with a - Nix store containing the closure of a bootable NixOS - configuration). - - - - - impureEnvVars - - This attribute allows you to specify a list of - environment variables that should be passed from the environment - of the calling user to the builder. Usually, the environment is - cleared completely when the builder is executed, but with this - attribute you can allow specific environment variables to be - passed unmodified. For example, fetchurl in - Nixpkgs has the line - - -impureEnvVars = [ "http_proxy" "https_proxy" ... ]; - - - to make it use the proxy server configuration specified by the - user in the environment variables http_proxy and - friends. - - This attribute is only allowed in fixed-output derivations, where - impurities such as these are okay since (the hash of) the output - is known in advance. It is ignored for all other - derivations. - - impureEnvVars implementation takes - environment variables from the current builder process. When a daemon is - building its environmental variables are used. Without the daemon, the - environmental variables come from the environment of the - nix-build. - - - - - - outputHash - outputHashAlgo - outputHashMode - - These attributes declare that the derivation is a - so-called fixed-output derivation, which - means that a cryptographic hash of the output is already known in - advance. When the build of a fixed-output derivation finishes, - Nix computes the cryptographic hash of the output and compares it - to the hash declared with these attributes. If there is a - mismatch, the build fails. - - The rationale for fixed-output derivations is derivations - such as those produced by the fetchurl - function. This function downloads a file from a given URL. To - ensure that the downloaded file has not been modified, the caller - must also specify a cryptographic hash of the file. For example, - - -fetchurl { - url = "http://ftp.gnu.org/pub/gnu/hello/hello-2.1.1.tar.gz"; - sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; -} - - - It sometimes happens that the URL of the file changes, e.g., - because servers are reorganised or no longer available. We then - must update the call to fetchurl, e.g., - - -fetchurl { - url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; - sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; -} - - - If a fetchurl derivation was treated like a - normal derivation, the output paths of the derivation and - all derivations depending on it would change. - For instance, if we were to change the URL of the Glibc source - distribution in Nixpkgs (a package on which almost all other - packages depend) massive rebuilds would be needed. This is - unfortunate for a change which we know cannot have a real effect - as it propagates upwards through the dependency graph. - - For fixed-output derivations, on the other hand, the name of - the output path only depends on the outputHash* - and name attributes, while all other attributes - are ignored for the purpose of computing the output path. (The - name attribute is included because it is part - of the path.) - - As an example, here is the (simplified) Nix expression for - fetchurl: - - -{ stdenv, curl }: # The curl program is used for downloading. - -{ url, sha256 }: - -stdenv.mkDerivation { - name = baseNameOf (toString url); - builder = ./builder.sh; - buildInputs = [ curl ]; - - # This is a fixed-output derivation; the output must be a regular - # file with SHA256 hash sha256. - outputHashMode = "flat"; - outputHashAlgo = "sha256"; - outputHash = sha256; - - inherit url; -} - - - - - The outputHashAlgo attribute specifies - the hash algorithm used to compute the hash. It can currently be - "sha1", "sha256" or - "sha512". - - The outputHashMode attribute determines - how the hash is computed. It must be one of the following two - values: - - - - "flat" - - The output must be a non-executable regular - file. If it isn’t, the build fails. The hash is simply - computed over the contents of that file (so it’s equal to what - Unix commands like sha256sum or - sha1sum produce). - - This is the default. - - - - "recursive" - - The hash is computed over the NAR archive dump - of the output (i.e., the result of nix-store - --dump). In this case, the output can be - anything, including a directory tree. - - - - - - - - The outputHash attribute, finally, must - be a string containing the hash in either hexadecimal or base-32 - notation. (See the nix-hash command - for information about converting to and from base-32 - notation.) - - - - - passAsFile - - A list of names of attributes that should be - passed via files rather than environment variables. For example, - if you have - - -passAsFile = ["big"]; -big = "a very long string"; - - - then when the builder runs, the environment variable - bigPath will contain the absolute path to a - temporary file containing a very long - string. That is, for any attribute - x listed in - passAsFile, Nix will pass an environment - variable xPath holding - the path of the file containing the value of attribute - x. This is useful when you need to pass - large strings to a builder, since most operating systems impose a - limit on the size of the environment (typically, a few hundred - kilobyte). - - - - - preferLocalBuild - - If this attribute is set to - true and distributed building is - enabled, then, if possible, the derivaton will be built - locally instead of forwarded to a remote machine. This is - appropriate for trivial builders where the cost of doing a - download or remote build would exceed the cost of building - locally. - - - - - allowSubstitutes - - - If this attribute is set to - false, then Nix will always build this - derivation; it will not try to substitute its outputs. This is - useful for very trivial derivations (such as - writeText in Nixpkgs) that are cheaper to - build than to substitute from a binary cache. - - You need to have a builder configured which satisfies - the derivation’s system attribute, since the - derivation cannot be substituted. Thus it is usually a good idea - to align system with - builtins.currentSystem when setting - allowSubstitutes to false. - For most trivial derivations this should be the case. - - - - - - - - -
diff --git a/doc/manual/expressions/arguments-variables.xml b/doc/manual/expressions/arguments-variables.xml deleted file mode 100644 index a4375c777..000000000 --- a/doc/manual/expressions/arguments-variables.xml +++ /dev/null @@ -1,114 +0,0 @@ -
- -Arguments and Variables - -The Nix expression in is a -function; it is missing some arguments that have to be filled in -somewhere. In the Nix Packages collection this is done in the file -pkgs/top-level/all-packages.nix, where all Nix -expressions for packages are imported and called with the appropriate -arguments. Here are some fragments of -all-packages.nix, with annotations of what they -mean: - - -... - -rec { ① - - hello = import ../applications/misc/hello/ex-1 ② { ③ - inherit fetchurl stdenv perl; - }; - - perl = import ../development/interpreters/perl { ④ - inherit fetchurl stdenv; - }; - - fetchurl = import ../build-support/fetchurl { - inherit stdenv; ... - }; - - stdenv = ...; - -} - - - - - - This file defines a set of attributes, all of which are - concrete derivations (i.e., not functions). In fact, we define a - mutually recursive set of attributes. That - is, the attributes can refer to each other. This is precisely - what we want since we want to plug the - various packages into each other. - - - - - Here we import the Nix expression for - GNU Hello. The import operation just loads and returns the - specified Nix expression. In fact, we could just have put the - contents of in - all-packages.nix at this point. That - would be completely equivalent, but it would make the file rather - bulky. - - Note that we refer to - ../applications/misc/hello/ex-1, not - ../applications/misc/hello/ex-1/default.nix. - When you try to import a directory, Nix automatically appends - /default.nix to the file name. - - - - - - This is where the actual composition takes place. Here we - call the function imported from - ../applications/misc/hello/ex-1 with a set - containing the things that the function expects, namely - fetchurl, stdenv, and - perl. We use inherit again to use the - attributes defined in the surrounding scope (we could also have - written fetchurl = fetchurl;, etc.). - - The result of this function call is an actual derivation - that can be built by Nix (since when we fill in the arguments of - the function, what we get is its body, which is the call to - stdenv.mkDerivation in ). - - Nixpkgs has a convenience function - callPackage that imports and calls a - function, filling in any missing arguments by passing the - corresponding attribute from the Nixpkgs set, like this: - - -hello = callPackage ../applications/misc/hello/ex-1 { }; - - - If necessary, you can set or override arguments: - - -hello = callPackage ../applications/misc/hello/ex-1 { stdenv = myStdenv; }; - - - - - - - - - Likewise, we have to instantiate Perl, - fetchurl, and the standard environment. - - - - - -
diff --git a/doc/manual/expressions/build-script.xml b/doc/manual/expressions/build-script.xml deleted file mode 100644 index 5c55954fc..000000000 --- a/doc/manual/expressions/build-script.xml +++ /dev/null @@ -1,114 +0,0 @@ -
- -Build Script - -Here is the builder referenced -from Hello's Nix expression (stored in -pkgs/applications/misc/hello/ex-1/builder.sh): - - -source $stdenv/setup ① - -PATH=$perl/bin:$PATH ② - -tar xvfz $src ③ -cd hello-* -./configure --prefix=$out ④ -make ⑤ -make install - -The builder can actually be made a lot shorter by using the -generic builder functions provided by -stdenv, but here we write out the build steps to -elucidate what a builder does. It performs the following -steps: - - - - - - When Nix runs a builder, it initially completely clears the - environment (except for the attributes declared in the - derivation). This is done to prevent undeclared inputs from being - used in the build process. If for example the - PATH contained /usr/bin, - then you might accidentally use - /usr/bin/gcc. - - So the first step is to set up the environment. This is - done by calling the setup script of the - standard environment. The environment variable - stdenv points to the location of the standard - environment being used. (It wasn't specified explicitly as an - attribute in , but - mkDerivation adds it automatically.) - - - - - - Since Hello needs Perl, we have to make sure that Perl is in - the PATH. The perl environment - variable points to the location of the Perl package (since it - was passed in as an attribute to the derivation), so - $perl/bin is the - directory containing the Perl interpreter. - - - - - - Now we have to unpack the sources. The - src attribute was bound to the result of - fetching the Hello source tarball from the network, so the - src environment variable points to the location in - the Nix store to which the tarball was downloaded. After - unpacking, we cd to the resulting source - directory. - - The whole build is performed in a temporary directory - created in /tmp, by the way. This directory is - removed after the builder finishes, so there is no need to clean - up the sources afterwards. Also, the temporary directory is - always newly created, so you don't have to worry about files from - previous builds interfering with the current build. - - - - - - GNU Hello is a typical Autoconf-based package, so we first - have to run its configure script. In Nix - every package is stored in a separate location in the Nix store, - for instance - /nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1. - Nix computes this path by cryptographically hashing all attributes - of the derivation. The path is passed to the builder through the - out environment variable. So here we give - configure the parameter - --prefix=$out to cause Hello to be installed in - the expected location. - - - - - - Finally we build Hello (make) and install - it into the location specified by out - (make install). - - - - - -If you are wondering about the absence of error checking on the -result of various commands called in the builder: this is because the -shell script is evaluated with Bash's option, -which causes the script to be aborted if any command fails without an -error check. - -
diff --git a/doc/manual/expressions/builtins.xml b/doc/manual/expressions/builtins.xml deleted file mode 100644 index 4ad481ad3..000000000 --- a/doc/manual/expressions/builtins.xml +++ /dev/null @@ -1,1663 +0,0 @@ -
- -Built-in Functions - -This section lists the functions and constants built into the -Nix expression evaluator. (The built-in function -derivation is discussed above.) Some built-ins, -such as derivation, are always in scope of every -Nix expression; you can just access them right away. But to prevent -polluting the namespace too much, most built-ins are not in scope. -Instead, you can access them through the builtins -built-in value, which is a set that contains all built-in functions -and values. For instance, derivation is also -available as builtins.derivation. - - - - - - - abort s - builtins.abort s - - Abort Nix expression evaluation, print error - message s. - - - - - - builtins.add - e1 e2 - - - Return the sum of the numbers - e1 and - e2. - - - - - - builtins.all - pred list - - Return true if the function - pred returns true - for all elements of list, - and false otherwise. - - - - - - builtins.any - pred list - - Return true if the function - pred returns true - for at least one element of list, - and false otherwise. - - - - - - builtins.attrNames - set - - Return the names of the attributes in the set - set in an alphabetically sorted list. For instance, - builtins.attrNames { y = 1; x = "foo"; } - evaluates to [ "x" "y" ]. - - - - - - builtins.attrValues - set - - Return the values of the attributes in the set - set in the order corresponding to the - sorted attribute names. - - - - - - baseNameOf s - - Return the base name of the - string s, that is, everything following - the final slash in the string. This is similar to the GNU - basename command. - - - - - - builtins.bitAnd - e1 e2 - - Return the bitwise AND of the integers - e1 and - e2. - - - - - - builtins.bitOr - e1 e2 - - Return the bitwise OR of the integers - e1 and - e2. - - - - - - builtins.bitXor - e1 e2 - - Return the bitwise XOR of the integers - e1 and - e2. - - - - - - builtins - - The set builtins contains all - the built-in functions and values. You can use - builtins to test for the availability of - features in the Nix installation, e.g., - - -if builtins ? getEnv then builtins.getEnv "PATH" else "" - - This allows a Nix expression to fall back gracefully on older Nix - installations that don’t have the desired built-in - function. - - - - - - builtins.compareVersions - s1 s2 - - Compare two strings representing versions and - return -1 if version - s1 is older than version - s2, 0 if they are - the same, and 1 if - s1 is newer than - s2. The version comparison algorithm - is the same as the one used by nix-env - -u. - - - - - - builtins.concatLists - lists - - Concatenate a list of lists into a single - list. - - - - - builtins.concatStringsSep - separator list - - Concatenate a list of strings with a separator - between each element, e.g. concatStringsSep "/" - ["usr" "local" "bin"] == "usr/local/bin" - - - - - builtins.currentSystem - - The built-in value currentSystem - evaluates to the Nix platform identifier for the Nix installation - on which the expression is being evaluated, such as - "i686-linux" or - "x86_64-darwin". - - - - - - - - - - - - builtins.deepSeq - e1 e2 - - This is like seq - e1 - e2, except that - e1 is evaluated - deeply: if it’s a list or set, its elements - or attributes are also evaluated recursively. - - - - - - derivation - attrs - builtins.derivation - attrs - - derivation is described in - . - - - - - - dirOf s - builtins.dirOf s - - Return the directory part of the string - s, that is, everything before the final - slash in the string. This is similar to the GNU - dirname command. - - - - - - builtins.div - e1 e2 - - Return the quotient of the numbers - e1 and - e2. - - - - - builtins.elem - x xs - - Return true if a value equal to - x occurs in the list - xs, and false - otherwise. - - - - - - builtins.elemAt - xs n - - Return element n from - the list xs. Elements are counted - starting from 0. A fatal error occurs if the index is out of - bounds. - - - - - - builtins.fetchurl - url - - Download the specified URL and return the path of - the downloaded file. This function is not available if restricted evaluation mode is - enabled. - - - - - - fetchTarball - url - builtins.fetchTarball - url - - Download the specified URL, unpack it and return - the path of the unpacked tree. The file must be a tape archive - (.tar) compressed with - gzip, bzip2 or - xz. The top-level path component of the files - in the tarball is removed, so it is best if the tarball contains a - single directory at top level. The typical use of the function is - to obtain external Nix expression dependencies, such as a - particular version of Nixpkgs, e.g. - - -with import (fetchTarball https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz) {}; - -stdenv.mkDerivation { … } - - - - The fetched tarball is cached for a certain amount of time - (1 hour by default) in ~/.cache/nix/tarballs/. - You can change the cache timeout either on the command line with - or - in the Nix configuration file with this option: - number of seconds to cache. - - - Note that when obtaining the hash with nix-prefetch-url - the option --unpack is required. - - - This function can also verify the contents against a hash. - In that case, the function takes a set instead of a URL. The set - requires the attribute url and the attribute - sha256, e.g. - - -with import (fetchTarball { - url = "https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz"; - sha256 = "1jppksrfvbk5ypiqdz4cddxdl8z6zyzdb2srq8fcffr327ld5jj2"; -}) {}; - -stdenv.mkDerivation { … } - - - - - This function is not available if restricted evaluation mode is - enabled. - - - - - - builtins.fetchGit - args - - - - - Fetch a path from git. args can be - a URL, in which case the HEAD of the repo at that URL is - fetched. Otherwise, it can be an attribute with the following - attributes (all except url optional): - - - - - url - - - The URL of the repo. - - - - - name - - - The name of the directory the repo should be exported to - in the store. Defaults to the basename of the URL. - - - - - rev - - - The git revision to fetch. Defaults to the tip of - ref. - - - - - ref - - - The git ref to look for the requested revision under. - This is often a branch or tag name. Defaults to - HEAD. - - - - By default, the ref value is prefixed - with refs/heads/. As of Nix 2.3.0 - Nix will not prefix refs/heads/ if - ref starts with refs/. - - - - - submodules - - - A Boolean parameter that specifies whether submodules - should be checked out. Defaults to - false. - - - - - - Here are some examples of how to use - fetchGit. - - - - - To fetch a private repository over SSH: - - builtins.fetchGit { - url = "git@github.com:my-secret/repository.git"; - ref = "master"; - rev = "adab8b916a45068c044658c4158d81878f9ed1c3"; -} - - - - - To fetch an arbitrary reference: - - builtins.fetchGit { - url = "https://github.com/NixOS/nix.git"; - ref = "refs/heads/0.5-release"; -} - - - - - If the revision you're looking for is in the default branch - of the git repository you don't strictly need to specify - the branch name in the ref attribute. - - - However, if the revision you're looking for is in a future - branch for the non-default branch you will need to specify - the the ref attribute as well. - - - builtins.fetchGit { - url = "https://github.com/nixos/nix.git"; - rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452"; - ref = "1.11-maintenance"; -} - - - - It is nice to always specify the branch which a revision - belongs to. Without the branch being specified, the - fetcher might fail if the default branch changes. - Additionally, it can be confusing to try a commit from a - non-default branch and see the fetch fail. If the branch - is specified the fault is much more obvious. - - - - - - - If the revision you're looking for is in the default branch - of the git repository you may omit the - ref attribute. - - builtins.fetchGit { - url = "https://github.com/nixos/nix.git"; - rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452"; -} - - - - To fetch a specific tag: - builtins.fetchGit { - url = "https://github.com/nixos/nix.git"; - ref = "refs/tags/1.9"; -} - - - - To fetch the latest version of a remote branch: - builtins.fetchGit { - url = "ssh://git@github.com/nixos/nix.git"; - ref = "master"; -} - Nix will refetch the branch in accordance to - . - This behavior is disabled in Pure - evaluation mode. - - - - - - - builtins.filter - f xs - - Return a list consisting of the elements of - xs for which the function - f returns - true. - - - - - - builtins.filterSource - e1 e2 - - - - This function allows you to copy sources into the Nix - store while filtering certain files. For instance, suppose that - you want to use the directory source-dir as - an input to a Nix expression, e.g. - - -stdenv.mkDerivation { - ... - src = ./source-dir; -} - - - However, if source-dir is a Subversion - working copy, then all those annoying .svn - subdirectories will also be copied to the store. Worse, the - contents of those directories may change a lot, causing lots of - spurious rebuilds. With filterSource you - can filter out the .svn directories: - - - src = builtins.filterSource - (path: type: type != "directory" || baseNameOf path != ".svn") - ./source-dir; - - - - - Thus, the first argument e1 - must be a predicate function that is called for each regular - file, directory or symlink in the source tree - e2. If the function returns - true, the file is copied to the Nix store, - otherwise it is omitted. The function is called with two - arguments. The first is the full path of the file. The second - is a string that identifies the type of the file, which is - either "regular", - "directory", "symlink" or - "unknown" (for other kinds of files such as - device nodes or fifos — but note that those cannot be copied to - the Nix store, so if the predicate returns - true for them, the copy will fail). If you - exclude a directory, the entire corresponding subtree of - e2 will be excluded. - - - - - - - - builtins.foldl’ - op nul list - - Reduce a list by applying a binary operator, from - left to right, e.g. foldl’ op nul [x0 x1 x2 ...] = op (op - (op nul x0) x1) x2) .... The operator is applied - strictly, i.e., its arguments are evaluated first. For example, - foldl’ (x: y: x + y) 0 [1 2 3] evaluates to - 6. - - - - - - builtins.functionArgs - f - - - Return a set containing the names of the formal arguments expected - by the function f. - The value of each attribute is a Boolean denoting whether the corresponding - argument has a default value. For instance, - functionArgs ({ x, y ? 123}: ...) = { x = false; y = true; }. - - - "Formal argument" here refers to the attributes pattern-matched by - the function. Plain lambdas are not included, e.g. - functionArgs (x: ...) = { }. - - - - - - builtins.fromJSON e - - Convert a JSON string to a Nix - value. For example, - - -builtins.fromJSON ''{"x": [1, 2, 3], "y": null}'' - - - returns the value { x = [ 1 2 3 ]; y = null; - }. - - - - - - builtins.genList - generator length - - Generate list of size - length, with each element - i equal to the value returned by - generator i. For - example, - - -builtins.genList (x: x * x) 5 - - - returns the list [ 0 1 4 9 16 ]. - - - - - - builtins.getAttr - s set - - getAttr returns the attribute - named s from - set. Evaluation aborts if the - attribute doesn’t exist. This is a dynamic version of the - . operator, since s - is an expression rather than an identifier. - - - - - - builtins.getEnv - s - - getEnv returns the value of - the environment variable s, or an empty - string if the variable doesn’t exist. This function should be - used with care, as it can introduce all sorts of nasty environment - dependencies in your Nix expression. - - getEnv is used in Nix Packages to - locate the file ~/.nixpkgs/config.nix, which - contains user-local settings for Nix Packages. (That is, it does - a getEnv "HOME" to locate the user’s home - directory.) - - - - - - builtins.hasAttr - s set - - hasAttr returns - true if set has an - attribute named s, and - false otherwise. This is a dynamic version of - the ? operator, since - s is an expression rather than an - identifier. - - - - - - builtins.hashString - type s - - Return a base-16 representation of the - cryptographic hash of string s. The - hash algorithm specified by type must - be one of "md5", "sha1", - "sha256" or "sha512". - - - - - - builtins.hashFile - type p - - Return a base-16 representation of the - cryptographic hash of the file at path p. The - hash algorithm specified by type must - be one of "md5", "sha1", - "sha256" or "sha512". - - - - - - builtins.head - list - - Return the first element of a list; abort - evaluation if the argument isn’t a list or is an empty list. You - can test whether a list is empty by comparing it with - []. - - - - - - import - path - builtins.import - path - - Load, parse and return the Nix expression in the - file path. If path - is a directory, the file default.nix - in that directory is loaded. Evaluation aborts if the - file doesn’t exist or contains an incorrect Nix expression. - import implements Nix’s module system: you - can put any Nix expression (such as a set or a function) in a - separate file, and use it from Nix expressions in other - files. - - Unlike some languages, import is a regular - function in Nix. Paths using the angle bracket syntax (e.g., - import <foo>) are normal path - values (see ). - - A Nix expression loaded by import must - not contain any free variables (identifiers - that are not defined in the Nix expression itself and are not - built-in). Therefore, it cannot refer to variables that are in - scope at the call site. For instance, if you have a calling - expression - - -rec { - x = 123; - y = import ./foo.nix; -} - - then the following foo.nix will give an - error: - - -x + 456 - - since x is not in scope in - foo.nix. If you want x - to be available in foo.nix, you should pass - it as a function argument: - - -rec { - x = 123; - y = import ./foo.nix x; -} - - and - - -x: x + 456 - - (The function argument doesn’t have to be called - x in foo.nix; any name - would work.) - - - - - - builtins.intersectAttrs - e1 e2 - - Return a set consisting of the attributes in the - set e2 that also exist in the set - e1. - - - - - - builtins.isAttrs - e - - Return true if - e evaluates to a set, and - false otherwise. - - - - - - builtins.isList - e - - Return true if - e evaluates to a list, and - false otherwise. - - - - - builtins.isFunction - e - - Return true if - e evaluates to a function, and - false otherwise. - - - - - - builtins.isString - e - - Return true if - e evaluates to a string, and - false otherwise. - - - - - - builtins.isInt - e - - Return true if - e evaluates to an int, and - false otherwise. - - - - - - builtins.isFloat - e - - Return true if - e evaluates to a float, and - false otherwise. - - - - - - builtins.isBool - e - - Return true if - e evaluates to a bool, and - false otherwise. - - - - builtins.isPath - e - - Return true if - e evaluates to a path, and - false otherwise. - - - - - isNull - e - builtins.isNull - e - - Return true if - e evaluates to null, - and false otherwise. - - This function is deprecated; - just write e == null instead. - - - - - - - - builtins.length - e - - Return the length of the list - e. - - - - - - builtins.lessThan - e1 e2 - - Return true if the number - e1 is less than the number - e2, and false - otherwise. Evaluation aborts if either - e1 or e2 - does not evaluate to a number. - - - - - - builtins.listToAttrs - e - - Construct a set from a list specifying the names - and values of each attribute. Each element of the list should be - a set consisting of a string-valued attribute - name specifying the name of the attribute, and - an attribute value specifying its value. - Example: - - -builtins.listToAttrs - [ { name = "foo"; value = 123; } - { name = "bar"; value = 456; } - ] - - - evaluates to - - -{ foo = 123; bar = 456; } - - - - - - - - map - f list - builtins.map - f list - - Apply the function f to - each element in the list list. For - example, - - -map (x: "foo" + x) [ "bar" "bla" "abc" ] - - evaluates to [ "foobar" "foobla" "fooabc" - ]. - - - - - - builtins.match - regex str - - Returns a list if the extended - POSIX regular expression regex - matches str precisely, otherwise returns - null. Each item in the list is a regex group. - - -builtins.match "ab" "abc" - - -Evaluates to null. - - -builtins.match "abc" "abc" - - -Evaluates to [ ]. - - -builtins.match "a(b)(c)" "abc" - - -Evaluates to [ "b" "c" ]. - - -builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" " FOO " - - -Evaluates to [ "foo" ]. - - - - - - builtins.mul - e1 e2 - - Return the product of the numbers - e1 and - e2. - - - - - - builtins.parseDrvName - s - - Split the string s into - a package name and version. The package name is everything up to - but not including the first dash followed by a digit, and the - version is everything following that dash. The result is returned - in a set { name, version }. Thus, - builtins.parseDrvName "nix-0.12pre12876" - returns { name = "nix"; version = "0.12pre12876"; - }. - - - - - - builtins.path - args - - - - - An enrichment of the built-in path type, based on the attributes - present in args. All are optional - except path: - - - - - path - - The underlying path. - - - - name - - - The name of the path when added to the store. This can - used to reference paths that have nix-illegal characters - in their names, like @. - - - - - filter - - - A function of the type expected by - builtins.filterSource, - with the same semantics. - - - - - recursive - - - When false, when - path is added to the store it is with a - flat hash, rather than a hash of the NAR serialization of - the file. Thus, path must refer to a - regular file, not a directory. This allows similar - behavior to fetchurl. Defaults to - true. - - - - - sha256 - - - When provided, this is the expected hash of the file at - the path. Evaluation will fail if the hash is incorrect, - and providing a hash allows - builtins.path to be used even when the - pure-eval nix config option is on. - - - - - - - - - builtins.pathExists - path - - Return true if the path - path exists at evaluation time, and - false otherwise. - - - - - builtins.placeholder - output - - Return a placeholder string for the specified - output that will be substituted by the - corresponding output path at build time. Typical outputs would be - "out", "bin" or - "dev". - - - - builtins.readDir - path - - Return the contents of the directory - path as a set mapping directory entries - to the corresponding file type. For instance, if directory - A contains a regular file - B and another directory - C, then builtins.readDir - ./A will return the set - - -{ B = "regular"; C = "directory"; } - - The possible values for the file type are - "regular", "directory", - "symlink" and - "unknown". - - - - - - builtins.readFile - path - - Return the contents of the file - path as a string. - - - - - - removeAttrs - set list - builtins.removeAttrs - set list - - Remove the attributes listed in - list from - set. The attributes don’t have to - exist in set. For instance, - - -removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ] - - evaluates to { y = 2; }. - - - - - - builtins.replaceStrings - from to s - - Given string s, replace - every occurrence of the strings in from - with the corresponding string in - to. For example, - - -builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar" - - - evaluates to "fabir". - - - - - - builtins.seq - e1 e2 - - Evaluate e1, then - evaluate and return e2. This ensures - that a computation is strict in the value of - e1. - - - - - - builtins.sort - comparator list - - Return list in sorted - order. It repeatedly calls the function - comparator with two elements. The - comparator should return true if the first - element is less than the second, and false - otherwise. For example, - - -builtins.sort builtins.lessThan [ 483 249 526 147 42 77 ] - - - produces the list [ 42 77 147 249 483 526 - ]. - - This is a stable sort: it preserves the relative order of - elements deemed equal by the comparator. - - - - - - builtins.split - regex str - - Returns a list composed of non matched strings interleaved - with the lists of the extended - POSIX regular expression regex matches - of str. Each item in the lists of matched - sequences is a regex group. - - -builtins.split "(a)b" "abc" - - -Evaluates to [ "" [ "a" ] "c" ]. - - -builtins.split "([ac])" "abc" - - -Evaluates to [ "" [ "a" ] "b" [ "c" ] "" ]. - - -builtins.split "(a)|(c)" "abc" - - -Evaluates to [ "" [ "a" null ] "b" [ null "c" ] "" ]. - - -builtins.split "([[:upper:]]+)" " FOO " - - -Evaluates to [ " " [ "FOO" ] " " ]. - - - - - - - builtins.splitVersion - s - - Split a string representing a version into its - components, by the same version splitting logic underlying the - version comparison in - nix-env -u. - - - - - - builtins.stringLength - e - - Return the length of the string - e. If e is - not a string, evaluation is aborted. - - - - - - builtins.sub - e1 e2 - - Return the difference between the numbers - e1 and - e2. - - - - - - builtins.substring - start len - s - - Return the substring of - s from character position - start (zero-based) up to but not - including start + len. If - start is greater than the length of the - string, an empty string is returned, and if start + - len lies beyond the end of the string, only the - substring up to the end of the string is returned. - start must be - non-negative. For example, - - -builtins.substring 0 3 "nixos" - - - evaluates to "nix". - - - - - - - builtins.tail - list - - Return the second to last elements of a list; - abort evaluation if the argument isn’t a list or is an empty - list. - - - - - - throw - s - builtins.throw - s - - Throw an error message - s. This usually aborts Nix expression - evaluation, but in nix-env -qa and other - commands that try to evaluate a set of derivations to get - information about those derivations, a derivation that throws an - error is silently skipped (which is not the case for - abort). - - - - - - builtins.toFile - name - s - - Store the string s in a - file in the Nix store and return its path. The file has suffix - name. This file can be used as an - input to derivations. One application is to write builders - “inline”. For instance, the following Nix expression combines - and into one file: - - -{ stdenv, fetchurl, perl }: - -stdenv.mkDerivation { - name = "hello-2.1.1"; - - builder = builtins.toFile "builder.sh" " - source $stdenv/setup - - PATH=$perl/bin:$PATH - - tar xvfz $src - cd hello-* - ./configure --prefix=$out - make - make install - "; - - src = fetchurl { - url = "http://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; - sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; - }; - inherit perl; -} - - - - It is even possible for one file to refer to another, e.g., - - - builder = let - configFile = builtins.toFile "foo.conf" " - # This is some dummy configuration file. - ... - "; - in builtins.toFile "builder.sh" " - source $stdenv/setup - ... - cp ${configFile} $out/etc/foo.conf - "; - - Note that ${configFile} is an antiquotation - (see ), so the result of the - expression configFile (i.e., a path like - /nix/store/m7p7jfny445k...-foo.conf) will be - spliced into the resulting string. - - It is however not allowed to have files - mutually referring to each other, like so: - - -let - foo = builtins.toFile "foo" "...${bar}..."; - bar = builtins.toFile "bar" "...${foo}..."; -in foo - - This is not allowed because it would cause a cyclic dependency in - the computation of the cryptographic hashes for - foo and bar. - It is also not possible to reference the result of a derivation. - If you are using Nixpkgs, the writeTextFile function is able to - do that. - - - - - - builtins.toJSON e - - Return a string containing a JSON representation - of e. Strings, integers, floats, booleans, - nulls and lists are mapped to their JSON equivalents. Sets - (except derivations) are represented as objects. Derivations are - translated to a JSON string containing the derivation’s output - path. Paths are copied to the store and represented as a JSON - string of the resulting store path. - - - - - - builtins.toPath s - - DEPRECATED. Use /. + "/path" - to convert a string into an absolute path. For relative paths, - use ./. + "/path". - - - - - - - toString e - builtins.toString e - - Convert the expression - e to a string. - e can be: - - A string (in which case the string is returned unmodified). - A path (e.g., toString /foo/bar yields "/foo/bar". - A set containing { __toString = self: ...; }. - An integer. - A list, in which case the string representations of its elements are joined with spaces. - A Boolean (false yields "", true yields "1"). - null, which yields the empty string. - - - - - - - - builtins.toXML e - - Return a string containing an XML representation - of e. The main application for - toXML is to communicate information with the - builder in a more structured format than plain environment - variables. - - - - Here is an example where this is - the case: - - - $out/server-conf.xml]]> ① ② - - - - - - - - - - - - - "; - - servlets = builtins.toXML []]> ③ - - The builder is supposed to generate the configuration file - for a Jetty servlet - container. A servlet container contains a number of - servlets (*.war files) each exported under a - specific URI prefix. So the servlet configuration is a list of - sets containing the path and - war of the servlet (). This kind of information is - difficult to communicate with the normal method of passing - information through an environment variable, which just - concatenates everything together into a string (which might just - work in this case, but wouldn’t work if fields are optional or - contain lists themselves). Instead the Nix expression is - converted to an XML representation with - toXML, which is unambiguous and can easily be - processed with the appropriate tools. For instance, in the - example an XSLT stylesheet (at point ②) is applied to it (at point - ①) to generate the XML configuration file for the Jetty server. - The XML representation produced at point ③ by - toXML is as follows: - - - - - - - - - - - - - - - - - - - - - -]]> - - Note that uses the toFile built-in to write the - builder and the stylesheet “inline” in the Nix expression. The - path of the stylesheet is spliced into the builder using the - syntax xsltproc ${stylesheet}. - - - - - - - - builtins.trace - e1 e2 - - Evaluate e1 and print its - abstract syntax representation on standard error. Then return - e2. This function is useful for - debugging. - - - - - builtins.tryEval - e - - Try to shallowly evaluate e. - Return a set containing the attributes success - (true if e evaluated - successfully, false if an error was thrown) and - value, equalling e - if successful and false otherwise. Note that this - doesn't evaluate e deeply, so - let e = { x = throw ""; }; in (builtins.tryEval e).success - will be true. Using builtins.deepSeq - one can get the expected result: let e = { x = throw ""; - }; in (builtins.tryEval (builtins.deepSeq e e)).success will be - false. - - - - - - - builtins.typeOf - e - - Return a string representing the type of the value - e, namely "int", - "bool", "string", - "path", "null", - "set", "list", - "lambda" or - "float". - - - - - - - -
diff --git a/doc/manual/expressions/derivations.xml b/doc/manual/expressions/derivations.xml deleted file mode 100644 index 0625bcdfe..000000000 --- a/doc/manual/expressions/derivations.xml +++ /dev/null @@ -1,210 +0,0 @@ -
- -Derivations - -The most important built-in function is -derivation, which is used to describe a single -derivation (a build action). It takes as input a set, the attributes -of which specify the inputs of the build. - - - - There must be an attribute - named system whose value must be a string - specifying a Nix system type, such as - "i686-linux" or - "x86_64-darwin". (To figure out your system type, - run nix -vv --version.) The build can only be - performed on a machine and operating system matching the system - type. (Nix can automatically forward builds for other platforms by - forwarding them to other machines; see .) - - There must be an attribute named - name whose value must be a string. This is used - as a symbolic name for the package by nix-env, - and it is appended to the output paths of the - derivation. - - There must be an attribute named - builder that identifies the program that is - executed to perform the build. It can be either a derivation or a - source (a local file reference, e.g., - ./builder.sh). - - Every attribute is passed as an environment variable - to the builder. Attribute values are translated to environment - variables as follows: - - - - Strings and numbers are just passed - verbatim. - - A path (e.g., - ../foo/sources.tar) causes the referenced - file to be copied to the store; its location in the store is put - in the environment variable. The idea is that all sources - should reside in the Nix store, since all inputs to a derivation - should reside in the Nix store. - - A derivation causes that - derivation to be built prior to the present derivation; its - default output path is put in the environment - variable. - - Lists of the previous types are also allowed. - They are simply concatenated, separated by - spaces. - - true is passed as the string - 1, false and - null are passed as an empty string. - - - - - - The optional attribute args - specifies command-line arguments to be passed to the builder. It - should be a list. - - The optional attribute outputs - specifies a list of symbolic outputs of the derivation. By default, - a derivation produces a single output path, denoted as - out. However, derivations can produce multiple - output paths. This is useful because it allows outputs to be - downloaded or garbage-collected separately. For instance, imagine a - library package that provides a dynamic library, header files, and - documentation. A program that links against the library doesn’t - need the header files and documentation at runtime, and it doesn’t - need the documentation at build time. Thus, the library package - could specify: - -outputs = [ "lib" "headers" "doc" ]; - - This will cause Nix to pass environment variables - lib, headers and - doc to the builder containing the intended store - paths of each output. The builder would typically do something like - -./configure --libdir=$lib/lib --includedir=$headers/include --docdir=$doc/share/doc - - for an Autoconf-style package. You can refer to each output of a - derivation by selecting it as an attribute, e.g. - -buildInputs = [ pkg.lib pkg.headers ]; - - The first element of outputs determines the - default output. Thus, you could also write - -buildInputs = [ pkg pkg.headers ]; - - since pkg is equivalent to - pkg.lib. - - - -The function mkDerivation in the Nixpkgs -standard environment is a wrapper around -derivation that adds a default value for -system and always uses Bash as the builder, to -which the supplied builder is passed as a command-line argument. See -the Nixpkgs manual for details. - -The builder is executed as follows: - - - - A temporary directory is created under the directory - specified by TMPDIR (default - /tmp) where the build will take place. The - current directory is changed to this directory. - - The environment is cleared and set to the derivation - attributes, as specified above. - - In addition, the following variables are set: - - - - NIX_BUILD_TOP contains the path of - the temporary directory for this build. - - Also, TMPDIR, - TEMPDIR, TMP, TEMP - are set to point to the temporary directory. This is to prevent - the builder from accidentally writing temporary files anywhere - else. Doing so might cause interference by other - processes. - - PATH is set to - /path-not-set to prevent shells from - initialising it to their built-in default value. - - HOME is set to - /homeless-shelter to prevent programs from - using /etc/passwd or the like to find the - user's home directory, which could cause impurity. Usually, when - HOME is set, it is used as the location of the home - directory, even if it points to a non-existent - path. - - NIX_STORE is set to the path of the - top-level Nix store directory (typically, - /nix/store). - - For each output declared in - outputs, the corresponding environment variable - is set to point to the intended path in the Nix store for that - output. Each output path is a concatenation of the cryptographic - hash of all build inputs, the name attribute - and the output name. (The output name is omitted if it’s - out.) - - - - - - If an output path already exists, it is removed. - Also, locks are acquired to prevent multiple Nix instances from - performing the same build at the same time. - - A log of the combined standard output and error is - written to /nix/var/log/nix. - - The builder is executed with the arguments specified - by the attribute args. If it exits with exit - code 0, it is considered to have succeeded. - - The temporary directory is removed (unless the - option was specified). - - If the build was successful, Nix scans each output - path for references to input paths by looking for the hash parts of - the input paths. Since these are potential runtime dependencies, - Nix registers them as dependencies of the output - paths. - - After the build, Nix sets the last-modified - timestamp on all files in the build result to 1 (00:00:01 1/1/1970 - UTC), sets the group to the default group, and sets the mode of the - file to 0444 or 0555 (i.e., read-only, with execute permission - enabled if the file was originally executable). Note that possible - setuid and setgid bits are - cleared. Setuid and setgid programs are not currently supported by - Nix. This is because the Nix archives used in deployment have no - concept of ownership information, and because it makes the build - result dependent on the user performing the build. - - - - - - - -
diff --git a/doc/manual/expressions/expression-language.xml b/doc/manual/expressions/expression-language.xml deleted file mode 100644 index 240ef80f1..000000000 --- a/doc/manual/expressions/expression-language.xml +++ /dev/null @@ -1,30 +0,0 @@ - - -Nix Expression Language - -The Nix expression language is a pure, lazy, functional -language. Purity means that operations in the language don't have -side-effects (for instance, there is no variable assignment). -Laziness means that arguments to functions are evaluated only when -they are needed. Functional means that functions are -normal values that can be passed around and manipulated -in interesting ways. The language is not a full-featured, general -purpose language. Its main job is to describe packages, -compositions of packages, and the variability within -packages. - -This section presents the various features of the -language. - - - - - - - - - diff --git a/doc/manual/expressions/expression-syntax.xml b/doc/manual/expressions/expression-syntax.xml deleted file mode 100644 index 853e40b58..000000000 --- a/doc/manual/expressions/expression-syntax.xml +++ /dev/null @@ -1,146 +0,0 @@ -
- -Expression Syntax - -Here is a Nix expression for GNU Hello: - - -{ stdenv, fetchurl, perl }: ① - -stdenv.mkDerivation { ② - name = "hello-2.1.1"; ③ - builder = ./builder.sh; ④ - src = fetchurl { ⑤ - url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz"; - sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465"; - }; - inherit perl; ⑥ -} - -This file is actually already in the Nix Packages collection in -pkgs/applications/misc/hello/ex-1/default.nix. -It is customary to place each package in a separate directory and call -the single Nix expression in that directory -default.nix. The file has the following elements -(referenced from the figure by number): - - - - - - This states that the expression is a - function that expects to be called with three - arguments: stdenv, fetchurl, - and perl. They are needed to build Hello, but - we don't know how to build them here; that's why they are function - arguments. stdenv is a package that is used - by almost all Nix Packages packages; it provides a - standard environment consisting of the things you - would expect in a basic Unix environment: a C/C++ compiler (GCC, - to be precise), the Bash shell, fundamental Unix tools such as - cp, grep, - tar, etc. fetchurl is a - function that downloads files. perl is the - Perl interpreter. - - Nix functions generally have the form { x, y, ..., - z }: e where x, y, - etc. are the names of the expected arguments, and where - e is the body of the function. So - here, the entire remainder of the file is the body of the - function; when given the required arguments, the body should - describe how to build an instance of the Hello package. - - - - - - So we have to build a package. Building something from - other stuff is called a derivation in Nix (as - opposed to sources, which are built by humans instead of - computers). We perform a derivation by calling - stdenv.mkDerivation. - mkDerivation is a function provided by - stdenv that builds a package from a set of - attributes. A set is just a list of - key/value pairs where each key is a string and each value is an - arbitrary Nix expression. They take the general form { - name1 = - expr1; ... - nameN = - exprN; }. - - - - - - The attribute name specifies the symbolic - name and version of the package. Nix doesn't really care about - these things, but they are used by for instance nix-env - -q to show a human-readable name for - packages. This attribute is required by - mkDerivation. - - - - - - The attribute builder specifies the - builder. This attribute can sometimes be omitted, in which case - mkDerivation will fill in a default builder - (which does a configure; make; make install, in - essence). Hello is sufficiently simple that the default builder - would suffice, but in this case, we will show an actual builder - for educational purposes. The value - ./builder.sh refers to the shell script shown - in , discussed below. - - - - - - The builder has to know what the sources of the package - are. Here, the attribute src is bound to the - result of a call to the fetchurl function. - Given a URL and a SHA-256 hash of the expected contents of the file - at that URL, this function builds a derivation that downloads the - file and checks its hash. So the sources are a dependency that - like all other dependencies is built before Hello itself is - built. - - Instead of src any other name could have - been used, and in fact there can be any number of sources (bound - to different attributes). However, src is - customary, and it's also expected by the default builder (which we - don't use in this example). - - - - - - Since the derivation requires Perl, we have to pass the - value of the perl function argument to the - builder. All attributes in the set are actually passed as - environment variables to the builder, so declaring an attribute - - -perl = perl; - - will do the trick: it binds an attribute perl - to the function argument which also happens to be called - perl. However, it looks a bit silly, so there - is a shorter syntax. The inherit keyword - causes the specified attributes to be bound to whatever variables - with the same name happen to be in scope. - - - - - - - -
diff --git a/doc/manual/expressions/generic-builder.xml b/doc/manual/expressions/generic-builder.xml deleted file mode 100644 index a6f258abc..000000000 --- a/doc/manual/expressions/generic-builder.xml +++ /dev/null @@ -1,98 +0,0 @@ -
- -Generic Builder Syntax - -Recall from that the builder -looked something like this: - - -PATH=$perl/bin:$PATH -tar xvfz $src -cd hello-* -./configure --prefix=$out -make -make install - -The builders for almost all Unix packages look like this — set up some -environment variables, unpack the sources, configure, build, and -install. For this reason the standard environment provides some Bash -functions that automate the build process. Here is what a builder -using the generic build facilities looks like: - - -buildInputs="$perl" ① - -source $stdenv/setup ② - -genericBuild ③ - -Here is what each line means: - - - - - - The buildInputs variable tells - setup to use the indicated packages as - inputs. This means that if a package provides a - bin subdirectory, it's added to - PATH; if it has a include - subdirectory, it's added to GCC's header search path; and so - on. (This is implemented in a modular way: - setup tries to source the file - pkg/nix-support/setup-hook - of all dependencies. These “setup hooks” can then set up whatever - environment variables they want; for instance, the setup hook for - Perl sets the PERL5LIB environment variable to - contain the lib/site_perl directories of all - inputs.) - - - - - - - The function genericBuild is defined in - the file $stdenv/setup. - - - - - - The final step calls the shell function - genericBuild, which performs the steps that - were done explicitly in . The - generic builder is smart enough to figure out whether to unpack - the sources using gzip, - bzip2, etc. It can be customised in many ways; - see the Nixpkgs manual for details. - - - - - - - -Discerning readers will note that the -buildInputs could just as well have been set in the Nix -expression, like this: - - - buildInputs = [ perl ]; - -The perl attribute can then be removed, and the -builder becomes even shorter: - - -source $stdenv/setup -genericBuild - -In fact, mkDerivation provides a default builder -that looks exactly like that, so it is actually possible to omit the -builder for Hello entirely. - -
diff --git a/doc/manual/expressions/language-constructs.xml b/doc/manual/expressions/language-constructs.xml deleted file mode 100644 index e1c589f61..000000000 --- a/doc/manual/expressions/language-constructs.xml +++ /dev/null @@ -1,408 +0,0 @@ -
- -Language Constructs - -
Recursive sets - -Recursive sets are just normal sets, but the attributes can -refer to each other. For example, - - -rec { - x = y; - y = 123; -}.x - - -evaluates to 123. Note that without -rec the binding x = y; would -refer to the variable y in the surrounding scope, -if one exists, and would be invalid if no such variable exists. That -is, in a normal (non-recursive) set, attributes are not added to the -lexical scope; in a recursive set, they are. - -Recursive sets of course introduce the danger of infinite -recursion. For example, the expression - - -rec { - x = y; - y = x; -}.x - -will crash with an infinite recursion encountered -error message. - -
- - -
Let-expressions - -A let-expression allows you to define local variables for an -expression. For instance, - - -let - x = "foo"; - y = "bar"; -in x + y - -evaluates to "foobar". - - - -
- - -
Inheriting attributes - -When defining a set or in a let-expression it is often convenient to copy variables -from the surrounding lexical scope (e.g., when you want to propagate -attributes). This can be shortened using the -inherit keyword. For instance, - - -let x = 123; in -{ inherit x; - y = 456; -} - -is equivalent to - - -let x = 123; in -{ x = x; - y = 456; -} - -and both evaluate to { x = 123; y = 456; }. (Note that -this works because x is added to the lexical scope -by the let construct.) It is also possible to -inherit attributes from another set. For instance, in this fragment -from all-packages.nix, - - - graphviz = (import ../tools/graphics/graphviz) { - inherit fetchurl stdenv libpng libjpeg expat x11 yacc; - inherit (xlibs) libXaw; - }; - - xlibs = { - libX11 = ...; - libXaw = ...; - ... - } - - libpng = ...; - libjpg = ...; - ... - -the set used in the function call to the function defined in -../tools/graphics/graphviz inherits a number of -variables from the surrounding scope (fetchurl -... yacc), but also inherits -libXaw (the X Athena Widgets) from the -xlibs (X11 client-side libraries) set. - - -Summarizing the fragment - - -... -inherit x y z; -inherit (src-set) a b c; -... - -is equivalent to - - -... -x = x; y = y; z = z; -a = src-set.a; b = src-set.b; c = src-set.c; -... - -when used while defining local variables in a let-expression or -while defining a set. - -
- - -
Functions - -Functions have the following form: - - -pattern: body - -The pattern specifies what the argument of the function must look -like, and binds variables in the body to (parts of) the -argument. There are three kinds of patterns: - - - - - If a pattern is a single identifier, then the - function matches any argument. Example: - - -let negate = x: !x; - concat = x: y: x + y; -in if negate true then concat "foo" "bar" else "" - - Note that concat is a function that takes one - argument and returns a function that takes another argument. This - allows partial parameterisation (i.e., only filling some of the - arguments of a function); e.g., - - -map (concat "foo") [ "bar" "bla" "abc" ] - - evaluates to [ "foobar" "foobla" - "fooabc" ]. - - - A set pattern of the form - { name1, name2, …, nameN } matches a set - containing the listed attributes, and binds the values of those - attributes to variables in the function body. For example, the - function - - -{ x, y, z }: z + y + x - - can only be called with a set containing exactly the attributes - x, y and - z. No other attributes are allowed. If you want - to allow additional arguments, you can use an ellipsis - (...): - - -{ x, y, z, ... }: z + y + x - - This works on any set that contains at least the three named - attributes. - - It is possible to provide default values - for attributes, in which case they are allowed to be missing. A - default value is specified by writing - name ? - e, where - e is an arbitrary expression. For example, - - -{ x, y ? "foo", z ? "bar" }: z + y + x - - specifies a function that only requires an attribute named - x, but optionally accepts y - and z. - - - An @-pattern provides a means of referring - to the whole value being matched: - - args@{ x, y, z, ... }: z + y + x + args.a - -but can also be written as: - - { x, y, z, ... } @ args: z + y + x + args.a - - Here args is bound to the entire argument, which - is further matched against the pattern { x, y, z, - ... }. @-pattern makes mainly sense with an - ellipsis(...) as you can access attribute names as - a, using args.a, which was given as an - additional attribute to the function. - - - - - The args@ expression is bound to the argument passed to the function which - means that attributes with defaults that aren't explicitly specified in the function call - won't cause an evaluation error, but won't exist in args. - - - For instance - -let - function = args@{ a ? 23, ... }: args; -in - function {} - - will evaluate to an empty attribute set. - - - - - -Note that functions do not have names. If you want to give them -a name, you can bind them to an attribute, e.g., - - -let concat = { x, y }: x + y; -in concat { x = "foo"; y = "bar"; } - - - -
- - -
Conditionals - -Conditionals look like this: - - -if e1 then e2 else e3 - -where e1 is an expression that should -evaluate to a Boolean value (true or -false). - -
- - -
Assertions - -Assertions are generally used to check that certain requirements -on or between features and dependencies hold. They look like this: - - -assert e1; e2 - -where e1 is an expression that should -evaluate to a Boolean value. If it evaluates to -true, e2 is returned; -otherwise expression evaluation is aborted and a backtrace is printed. - -Here is a Nix expression for the Subversion package that shows -how assertions can be used:. - - -{ localServer ? false -, httpServer ? false -, sslSupport ? false -, pythonBindings ? false -, javaSwigBindings ? false -, javahlBindings ? false -, stdenv, fetchurl -, openssl ? null, httpd ? null, db4 ? null, expat, swig ? null, j2sdk ? null -}: - -assert localServer -> db4 != null; ① -assert httpServer -> httpd != null && httpd.expat == expat; ② -assert sslSupport -> openssl != null && (httpServer -> httpd.openssl == openssl); ③ -assert pythonBindings -> swig != null && swig.pythonSupport; -assert javaSwigBindings -> swig != null && swig.javaSupport; -assert javahlBindings -> j2sdk != null; - -stdenv.mkDerivation { - name = "subversion-1.1.1"; - ... - openssl = if sslSupport then openssl else null; ④ - ... -} - -The points of interest are: - - - - - This assertion states that if Subversion is to have support - for local repositories, then Berkeley DB is needed. So if the - Subversion function is called with the - localServer argument set to - true but the db4 argument - set to null, then the evaluation fails. - - - - This is a more subtle condition: if Subversion is built with - Apache (httpServer) support, then the Expat - library (an XML library) used by Subversion should be same as the - one used by Apache. This is because in this configuration - Subversion code ends up being linked with Apache code, and if the - Expat libraries do not match, a build- or runtime link error or - incompatibility might occur. - - - - This assertion says that in order for Subversion to have SSL - support (so that it can access https URLs), an - OpenSSL library must be passed. Additionally, it says that - if Apache support is enabled, then Apache's - OpenSSL should match Subversion's. (Note that if Apache support - is not enabled, we don't care about Apache's OpenSSL.) - - - - The conditional here is not really related to assertions, - but is worth pointing out: it ensures that if SSL support is - disabled, then the Subversion derivation is not dependent on - OpenSSL, even if a non-null value was passed. - This prevents an unnecessary rebuild of Subversion if OpenSSL - changes. - - - - -
- - - -
With-expressions - -A with-expression, - - -with e1; e2 - -introduces the set e1 into the lexical -scope of the expression e2. For instance, - - -let as = { x = "foo"; y = "bar"; }; -in with as; x + y - -evaluates to "foobar" since the -with adds the x and -y attributes of as to the -lexical scope in the expression x + y. The most -common use of with is in conjunction with the -import function. E.g., - - -with (import ./definitions.nix); ... - -makes all attributes defined in the file -definitions.nix available as if they were defined -locally in a let-expression. - -The bindings introduced by with do not shadow bindings -introduced by other means, e.g. - - -let a = 3; in with { a = 1; }; let a = 4; in with { a = 2; }; ... - -establishes the same scope as - - -let a = 1; in let a = 2; in let a = 3; in let a = 4; in ... - - - -
- - -
Comments - -Comments can be single-line, started with a # -character, or inline/multi-line, enclosed within /* -... */. - -
- - -
diff --git a/doc/manual/expressions/language-operators.xml b/doc/manual/expressions/language-operators.xml deleted file mode 100644 index 7f69bfcef..000000000 --- a/doc/manual/expressions/language-operators.xml +++ /dev/null @@ -1,222 +0,0 @@ -
- -Operators - - lists the operators in the -Nix expression language, in order of precedence (from strongest to -weakest binding). - - - Operators - - - - Name - Syntax - Associativity - Description - Precedence - - - - - Select - e . - attrpath - [ or def ] - - none - Select attribute denoted by the attribute path - attrpath from set - e. (An attribute path is a - dot-separated list of attribute names.) If the attribute - doesn’t exist, return def if - provided, otherwise abort evaluation. - 1 - - - Application - e1 e2 - left - Call function e1 with - argument e2. - 2 - - - Arithmetic Negation - - e - none - Arithmetic negation. - 3 - - - Has Attribute - e ? - attrpath - none - Test whether set e contains - the attribute denoted by attrpath; - return true or - false. - 4 - - - List Concatenation - e1 ++ e2 - right - List concatenation. - 5 - - - Multiplication - - e1 * e2, - - left - Arithmetic multiplication. - 6 - - - Division - - e1 / e2 - - left - Arithmetic division. - 6 - - - Addition - - e1 + e2 - - left - Arithmetic addition. - 7 - - - Subtraction - - e1 - e2 - - left - Arithmetic subtraction. - 7 - - - String Concatenation - - string1 + string2 - - left - String concatenation. - 7 - - - Not - ! e - none - Boolean negation. - 8 - - - Update - e1 // - e2 - right - Return a set consisting of the attributes in - e1 and - e2 (with the latter taking - precedence over the former in case of equally named - attributes). - 9 - - - Less Than - - e1 < e2, - - none - Arithmetic comparison. - 10 - - - Less Than or Equal To - - e1 <= e2 - - none - Arithmetic comparison. - 10 - - - Greater Than - - e1 > e2 - - none - Arithmetic comparison. - 10 - - - Greater Than or Equal To - - e1 >= e2 - - none - Arithmetic comparison. - 10 - - - Equality - - e1 == e2 - - none - Equality. - 11 - - - Inequality - - e1 != e2 - - none - Inequality. - 11 - - - Logical AND - e1 && - e2 - left - Logical AND. - 12 - - - Logical OR - e1 || - e2 - left - Logical OR. - 13 - - - Logical Implication - e1 -> - e2 - none - Logical implication (equivalent to - !e1 || - e2). - 14 - - - -
- -
diff --git a/doc/manual/expressions/language-values.xml b/doc/manual/expressions/language-values.xml deleted file mode 100644 index 5520a4938..000000000 --- a/doc/manual/expressions/language-values.xml +++ /dev/null @@ -1,312 +0,0 @@ -
- -Values - - -
Simple Values - -Nix has the following basic data types: - - - - - - Strings can be written in three - ways. - - The most common way is to enclose the string between double - quotes, e.g., "foo bar". Strings can span - multiple lines. The special characters " and - \ and the character sequence - ${ must be escaped by prefixing them with a - backslash (\). Newlines, carriage returns and - tabs can be written as \n, - \r and \t, - respectively. - - You can include the result of an expression into a string by - enclosing it in - ${...}, a feature - known as antiquotation. The enclosed - expression must evaluate to something that can be coerced into a - string (meaning that it must be a string, a path, or a - derivation). For instance, rather than writing - - -"--with-freetype2-library=" + freetype + "/lib" - - (where freetype is a derivation), you can - instead write the more natural - - -"--with-freetype2-library=${freetype}/lib" - - The latter is automatically translated to the former. A more - complicated example (from the Nix expression for Qt): - - -configureFlags = " - -system-zlib -system-libpng -system-libjpeg - ${if openglSupport then "-dlopen-opengl - -L${mesa}/lib -I${mesa}/include - -L${libXmu}/lib -I${libXmu}/include" else ""} - ${if threadSupport then "-thread" else "-no-thread"} -"; - - Note that Nix expressions and strings can be arbitrarily nested; - in this case the outer string contains various antiquotations that - themselves contain strings (e.g., "-thread"), - some of which in turn contain expressions (e.g., - ${mesa}). - - The second way to write string literals is as an - indented string, which is enclosed between - pairs of double single-quotes, like so: - - -'' - This is the first line. - This is the second line. - This is the third line. -'' - - This kind of string literal intelligently strips indentation from - the start of each line. To be precise, it strips from each line a - number of spaces equal to the minimal indentation of the string as - a whole (disregarding the indentation of empty lines). For - instance, the first and second line are indented two space, while - the third line is indented four spaces. Thus, two spaces are - stripped from each line, so the resulting string is - - -"This is the first line.\nThis is the second line.\n This is the third line.\n" - - - - Note that the whitespace and newline following the opening - '' is ignored if there is no non-whitespace - text on the initial line. - - Antiquotation - (${expr}) is - supported in indented strings. - - Since ${ and '' have - special meaning in indented strings, you need a way to quote them. - $ can be escaped by prefixing it with - '' (that is, two single quotes), i.e., - ''$. '' can be escaped by - prefixing it with ', i.e., - '''. $ removes any special meaning - from the following $. Linefeed, carriage-return and tab - characters can be written as ''\n, - ''\r, ''\t, and ''\ - escapes any other character. - - - - Indented strings are primarily useful in that they allow - multi-line string literals to follow the indentation of the - enclosing Nix expression, and that less escaping is typically - necessary for strings representing languages such as shell scripts - and configuration files because '' is much less - common than ". Example: - - -stdenv.mkDerivation { - ... - postInstall = - '' - mkdir $out/bin $out/etc - cp foo $out/bin - echo "Hello World" > $out/etc/foo.conf - ${if enableBar then "cp bar $out/bin" else ""} - ''; - ... -} - - - - - Finally, as a convenience, URIs as - defined in appendix B of RFC 2396 - can be written as is, without quotes. For - instance, the string - "http://example.org/foo.tar.bz2" - can also be written as - http://example.org/foo.tar.bz2. - - - - Numbers, which can be integers (like - 123) or floating point (like - 123.43 or .27e13). - - Numbers are type-compatible: pure integer operations will always - return integers, whereas any operation involving at least one floating point - number will have a floating point number as a result. - - Paths, e.g., - /bin/sh or ./builder.sh. - A path must contain at least one slash to be recognised as such. For - instance, builder.sh is not a path: it's parsed - as an expression that selects the attribute sh - from the variable builder. If the file name is - relative, i.e., if it does not begin with a slash, it is made - absolute at parse time relative to the directory of the Nix - expression that contained it. For instance, if a Nix expression in - /foo/bar/bla.nix refers to - ../xyzzy/fnord.nix, the absolute path is - /foo/xyzzy/fnord.nix. - - If the first component of a path is a ~, - it is interpreted as if the rest of the path were relative to the - user's home directory. e.g. ~/foo would be - equivalent to /home/edolstra/foo for a user - whose home directory is /home/edolstra. - - - Paths can also be specified between angle brackets, e.g. - <nixpkgs>. This means that the directories - listed in the environment variable - NIX_PATH will be searched - for the given file or directory name. - - - - - Booleans with values - true and - false. - - The null value, denoted as - null. - - - - - -
- - -
Lists - -Lists are formed by enclosing a whitespace-separated list of -values between square brackets. For example, - - -[ 123 ./foo.nix "abc" (f { x = y; }) ] - -defines a list of four elements, the last being the result of a call -to the function f. Note that function calls have -to be enclosed in parentheses. If they had been omitted, e.g., - - -[ 123 ./foo.nix "abc" f { x = y; } ] - -the result would be a list of five elements, the fourth one being a -function and the fifth being a set. - -Note that lists are only lazy in values, and they are strict in length. - - -
- - -
Sets - -Sets are really the core of the language, since ultimately the -Nix language is all about creating derivations, which are really just -sets of attributes to be passed to build scripts. - -Sets are just a list of name/value pairs (called -attributes) enclosed in curly brackets, where -each value is an arbitrary expression terminated by a semicolon. For -example: - - -{ x = 123; - text = "Hello"; - y = f { bla = 456; }; -} - -This defines a set with attributes named x, -text, y. The order of the -attributes is irrelevant. An attribute name may only occur -once. - -Attributes can be selected from a set using the -. operator. For instance, - - -{ a = "Foo"; b = "Bar"; }.a - -evaluates to "Foo". It is possible to provide a -default value in an attribute selection using the -or keyword. For example, - - -{ a = "Foo"; b = "Bar"; }.c or "Xyzzy" - -will evaluate to "Xyzzy" because there is no -c attribute in the set. - -You can use arbitrary double-quoted strings as attribute -names: - - -{ "foo ${bar}" = 123; "nix-1.0" = 456; }."foo ${bar}" - - -This will evaluate to 123 (Assuming -bar is antiquotable). In the case where an -attribute name is just a single antiquotation, the quotes can be -dropped: - - -{ foo = 123; }.${bar} or 456 - -This will evaluate to 123 if -bar evaluates to "foo" when -coerced to a string and 456 otherwise (again -assuming bar is antiquotable). - -In the special case where an attribute name inside of a set declaration -evaluates to null (which is normally an error, as -null is not antiquotable), that attribute is simply not -added to the set: - - -{ ${if foo then "bar" else null} = true; } - -This will evaluate to {} if foo -evaluates to false. - -A set that has a __functor attribute whose value -is callable (i.e. is itself a function or a set with a -__functor attribute whose value is callable) can be -applied as if it were a function, with the set itself passed in first -, e.g., - - -let add = { __functor = self: x: x + self.x; }; - inc = add // { x = 1; }; -in inc 1 - - -evaluates to 2. This can be used to attach metadata to a -function without the caller needing to treat it specially, or to implement -a form of object-oriented programming, for example. - - - -
- - -
diff --git a/doc/manual/expressions/simple-building-testing.xml b/doc/manual/expressions/simple-building-testing.xml deleted file mode 100644 index f82223df9..000000000 --- a/doc/manual/expressions/simple-building-testing.xml +++ /dev/null @@ -1,76 +0,0 @@ -
- -Building and Testing - -You can now try to build Hello. Of course, you could do -nix-env -i hello, but you may not want to install a -possibly broken package just yet. The best way to test the package is by -using the command nix-build, -which builds a Nix expression and creates a symlink named -result in the current directory: - - -$ nix-build -A hello -building path `/nix/store/632d2b22514d...-hello-2.1.1' -hello-2.1.1/ -hello-2.1.1/intl/ -hello-2.1.1/intl/ChangeLog -... - -$ ls -l result -lrwxrwxrwx ... 2006-09-29 10:43 result -> /nix/store/632d2b22514d...-hello-2.1.1 - -$ ./result/bin/hello -Hello, world! - -The option selects -the hello attribute. This is faster than using the -symbolic package name specified by the name -attribute (which also happens to be hello) and is -unambiguous (there can be multiple packages with the symbolic name -hello, but there can be only one attribute in a set -named hello). - -nix-build registers the -./result symlink as a garbage collection root, so -unless and until you delete the ./result symlink, -the output of the build will be safely kept on your system. You can -use nix-build’s switch to give the symlink another -name. - -Nix has transactional semantics. Once a build finishes -successfully, Nix makes a note of this in its database: it registers -that the path denoted by out is now -valid. If you try to build the derivation again, Nix -will see that the path is already valid and finish immediately. If a -build fails, either because it returns a non-zero exit code, because -Nix or the builder are killed, or because the machine crashes, then -the output paths will not be registered as valid. If you try to build -the derivation again, Nix will remove the output paths if they exist -(e.g., because the builder died half-way through make -install) and try again. Note that there is no -negative caching: Nix doesn't remember that a build -failed, and so a failed build can always be repeated. This is because -Nix cannot distinguish between permanent failures (e.g., a compiler -error due to a syntax error in the source) and transient failures -(e.g., a disk full condition). - -Nix also performs locking. If you run multiple Nix builds -simultaneously, and they try to build the same derivation, the first -Nix instance that gets there will perform the build, while the others -block (or perform other derivations if available) until the build -finishes: - - -$ nix-build -A hello -waiting for lock on `/nix/store/0h5b7hp8d4hqfrw8igvx97x1xawrjnac-hello-2.1.1x' - -So it is always safe to run multiple instances of Nix in parallel -(which isn’t the case with, say, make). - -
diff --git a/doc/manual/expressions/simple-expression.xml b/doc/manual/expressions/simple-expression.xml deleted file mode 100644 index ad97220a8..000000000 --- a/doc/manual/expressions/simple-expression.xml +++ /dev/null @@ -1,46 +0,0 @@ - - -A Simple Nix Expression - -This section shows how to add and test the GNU Hello -package to the Nix Packages collection. Hello is a program -that prints out the text Hello, world!. - -To add a package to the Nix Packages collection, you generally -need to do three things: - - - - Write a Nix expression for the package. This is a - file that describes all the inputs involved in building the package, - such as dependencies, sources, and so on. - - Write a builder. This is a - shell script that builds the package from the inputs. (In fact, it - can be written in any language, but typically it's a - bash shell script.) - - Add the package to the file - pkgs/top-level/all-packages.nix. The Nix - expression written in the first step is a - function; it requires other packages in order - to build it. In this step you put it all together, i.e., you call - the function with the right arguments to build the actual - package. - - - - - - - - - - - - diff --git a/doc/manual/expressions/writing-nix-expressions.xml b/doc/manual/expressions/writing-nix-expressions.xml deleted file mode 100644 index 6646dddf0..000000000 --- a/doc/manual/expressions/writing-nix-expressions.xml +++ /dev/null @@ -1,26 +0,0 @@ - - -Writing Nix Expressions - - -This chapter shows you how to write Nix expressions, which -instruct Nix how to build packages. It starts with a -simple example (a Nix expression for GNU Hello), and then moves -on to a more in-depth look at the Nix expression language. - -This chapter is mostly about the Nix expression language. -For more extensive information on adding packages to the Nix Packages -collection (such as functions in the standard environment and coding -conventions), please consult its -manual. - - - - - - -- cgit v1.2.3