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path: root/src/libexpr/nixexpr.hh
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2013-02-08Make "${./path} ..." evaluate to a string, not a pathEelco Dolstra
Wacky string coercion semantics caused expressions like exec = "${./my-script} params..."; to evaluate to a path (‘/path/my-script params’), because anti-quotations are desuged to string concatenation: exec = ./my-script + " params..."; By constrast, adding a space at the start would yield a string as expected: exec = " ${./my-script} params..."; Now the first example also evaluates to a string.
2012-08-12Add some basic profiling support to the evaluatorEelco Dolstra
Setting the environment variable NIX_COUNT_CALLS to 1 enables some basic profiling in the evaluator. It will count calls to functions and primops as well as evaluations of attributes. For example, to see where evaluation of a NixOS configuration spends its time: $ NIX_SHOW_STATS=1 NIX_COUNT_CALLS=1 ./src/nix-instantiate/nix-instantiate '<nixos>' -A system --readonly-mode ... calls to 39 primops: 239532 head 233962 tail 191252 hasAttr ... calls to 1595 functions: 224157 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:19' 221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:14' 221767 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/lists.nix:17:10' ... evaluations of 7088 attributes: 167377 undefined position 132459 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:119:41' 47322 `/nix/var/nix/profiles/per-user/root/channels/nixos/nixpkgs/pkgs/lib/attrsets.nix:13:21' ...
2012-07-18Use "#pragma once" to prevent repeated header file inclusionEelco Dolstra
2012-01-07* Don't create thunks for simple constants (integers, strings, paths)Eelco Dolstra
and allocate them only once. * Move Value and related functions into value.hh.
2012-01-04* Don't use dynamic_cast, it's very slow. "nix-instantiateEelco Dolstra
/etc/nixos/nixos -A system" spent about 10% of its time in dynamic_cast.
2011-07-13* Allow a default value in attribute selection by writingEelco Dolstra
x.y.z or default (as originally proposed in https://mail.cs.uu.nl/pipermail/nix-dev/2009-September/002989.html). For instance, an expression like stdenv.lib.attrByPath ["features" "ckSched"] false args can now be written as args.features.ckSched or false
2011-07-06* Change the right-hand side of the ‘.’ operator from an attribute toEelco Dolstra
an attribute path. This is a refactoring to support default values.
2011-07-06* In the ‘?’ operator, allow attribute paths. For instance, you canEelco Dolstra
write ‘attrs ? a.b’ to test whether ‘attrs’ has an attribute ‘a’ containing an attribute ‘b’. This is more convenient than ‘attrs ? a && attrs.a ? b’. Slight change in the semantics: it's no longer an error if the left-hand side of ‘?’ is not an attribute set. In that case it just returns false. So, ‘null ? foo’ no longer throws an error.
2010-10-24* Keep attribute sets in sorted order to speed up attribute lookups.Eelco Dolstra
* Simplify the representation of attributes in the AST. * Change the behaviour of listToAttrs() in case of duplicate names.
2010-10-23* Optimise string constants by putting them in the symbol table.Eelco Dolstra
2010-10-22* Store Value nodes outside of attribute sets. I.e., Attr now storesEelco Dolstra
a pointer to a Value, rather than the Value directly. This improves the effectiveness of garbage collection a lot: if the Value is stored inside the set directly, then any live pointer to the Value causes all other attributes in the set to be live as well.
2010-10-04* Make sure that config.h is included before the system headers,Eelco Dolstra
because it defines _FILE_OFFSET_BITS. Without this, on OpenSolaris the system headers define it to be 32, and then the 32-bit stat() ends up being called with a 64-bit "struct stat", or vice versa. This also ensures that we get 64-bit file sizes everywhere. * Remove the redundant call to stat() in parseExprFromFile(). The file cannot be a symlink because that's the exit condition of the loop before.
2010-06-01* Turn build errors during evaluation into EvalErrors.Eelco Dolstra
2010-05-07* Store position info for inherited attributes.Eelco Dolstra
2010-05-06* Store attribute positions in the AST and report duplicate attributeEelco Dolstra
errors with position info. * For all positions, use the position of the first character of the first token, rather than the last character of the first token plus one.
2010-04-22* Simplify the implementation of `with'. This gives a 7% speedup inEelco Dolstra
evaluating the NixOS system configuration.
2010-04-22* Check for duplicate attribute names / function arguments. `makeEelco Dolstra
check' now succeeds :-) * An attribute set such as `{ foo = { enable = true; }; foo.port = 23; }' now parses. It was previously rejected, but I'm too lazy to implement the check. (The only reason to reject it is that the reverse, `{ foo.port = 23; foo = { enable = true; }; }', is rejected, which is kind of ugly.)
2010-04-14* Implemented inherit.Eelco Dolstra
2010-04-14* Refactoring: move variable uses to a separate class.Eelco Dolstra
2010-04-14* Implemented withs.Eelco Dolstra
2010-04-14* After parsing, compute level/displacement pairs for each variableEelco Dolstra
use site, allowing environments to be stores as vectors of values rather than maps. This should speed up evaluation and reduce the number of allocations.
2010-04-14* Remove more obsolete code.Eelco Dolstra
2010-04-13* Evaluate lets directly (i.e. without desugaring to `rec { attrs...;Eelco Dolstra
<let-body> = e; }.<let-body>). This prevents the unnecessary allocation of an attribute set.
2010-04-13* Use a symbol table to represent identifiers and attribute namesEelco Dolstra
efficiently. The symbol table ensures that there is only one copy of each symbol, thus allowing symbols to be compared efficiently using a pointer equality test.
2010-04-12* Indented strings.Eelco Dolstra
2010-04-12* More missing constructs.Eelco Dolstra
2010-04-12* Don't use ATerms for the abstract syntax trees anymore. NotEelco Dolstra
finished yet.
2010-04-08* Remove a lot of dead code.Eelco Dolstra
2009-05-15* Some syntactic sugar for attribute sets: allow {x.y.z = ...;} as aEelco Dolstra
shorthand for {x = {y = {z = ...;};};}. This is especially useful for NixOS configuration files, e.g. { services = { sshd = { enable = true; port = 2022; }; }; } can now be written as { services.sshd.enable = true; services.sshd.port = 2022; } However, it is currently not permitted to write { services.sshd = {enable = true;}; services.sshd.port = 2022; } as this is considered a duplicate definition of `services.sshd'.
2008-08-14* Added an experimental feature suggested by Andres: ellipses ("...")Eelco Dolstra
in attribute set pattern matches. This allows defining a function that takes *at least* the listed attributes, while ignoring additional attributes. For instance, {stdenv, fetchurl, fuse, ...}: stdenv.mkDerivation { ... }; defines a function that requires an attribute set that contains the specified attributes but ignores others. The main advantage is that we can then write in all-packages.nix aefs = import ../bla/aefs pkgs; instead of aefs = import ../bla/aefs { inherit stdenv fetchurl fuse; }; This saves a lot of typing (not to mention not having to update all-packages.nix with purely mechanical changes). It saves as much typing as the "args: with args;" style, but has the advantage that the function arguments are properly declared (not implicit in what the body of the "with" uses).
2008-08-14* Refactoring: combine functions that take an attribute set andEelco Dolstra
functions that take a single argument (plain lambdas) into one AST node (Function) that contains a Pattern node describing the arguments. Current patterns are single lazy arguments (VarPat) and matching against an attribute set (AttrsPat). This refactoring allows other kinds of patterns to be added easily, such as Haskell-style @-patterns, or list pattern matching.
2007-04-16* New primop "throw <string>" to throw an error. This is like abort,Eelco Dolstra
only thrown errors are caught by the top-level derivation evaluation in nix-env -qa / -i.
2007-02-02* nix-env now maintains meta info (from the `meta' derivationEelco Dolstra
attribute) about installed packages in user environments. Thus, an operation like `nix-env -q --description' shows useful information not only on available packages but also on installed packages. * nix-env now passes the entire manifest as an argument to the Nix expression of the user environment builder (not just a list of paths), so that in particular the user environment builder has access to the meta attributes. * New operation `--set-flag' in nix-env to change meta info of installed packages. This will be useful to pass per-package policies to the user environment builder (e.g., how to resolve collision or whether to disable a package (NIX-80)) or upgrade policies in nix-env (e.g., that a package should be "masked", that is, left untouched by upgrade actions). Example: $ nix-env --set-flag enabled false ghc-6.4
2007-01-13* Canonicalise ASTs in `nix-instantiate --eval': remove positionEelco Dolstra
info, sort attribute sets.
2006-10-16* Big cleanup of the semantics of paths, strings, contexts, stringEelco Dolstra
concatenation and string coercion. This was a big mess (see e.g. NIX-67). Contexts are now folded into strings, so that they don't cause evaluation errors when they're not expected. The semantics of paths has been clarified (see nixexpr-ast.def). toString() and coerceToString() have been merged. Semantic change: paths are now copied to the store when they're in a concatenation (and in most other situations - that's the formalisation of the meaning of a path). So "foo " + ./bla evaluates to "foo /nix/store/hash...-bla", not "foo /path/to/current-dir/bla". This prevents accidental impurities, and is more consistent with the treatment of derivation outputs, e.g., `"foo " + bla' where `bla' is a derivation. (Here `bla' would be replaced by the output path of `bla'.)
2006-09-20* Shut up a warning.Eelco Dolstra
2006-09-04* Remove unnecessary inclusions of aterm2.h.Eelco Dolstra
2006-09-04* Use a proper namespace.Eelco Dolstra
* Optimise header file usage a bit. * Compile the parser as C++.
2006-08-23* New primop: abort "error message".Eelco Dolstra
2006-08-04* Fix a few warnings.Eelco Dolstra
2006-07-28* `nix-instantiate --print-args': print out the valid values forEelco Dolstra
functions arguments that have a domain.
2006-07-24* Refactoring to support domain checks.Eelco Dolstra
2006-07-19* Better error messages (especially wrt types).Eelco Dolstra
2006-05-04* Use the new ATermMap.Eelco Dolstra
2006-05-02* Use a linked list of substitutions. This reduces the amount ofEelco Dolstra
copying.
2006-03-06* GCC 4.1 compatibility.Eelco Dolstra
2005-05-08* ATermMap needs an assignment operator, otherwise we are screwed.Eelco Dolstra
2005-04-10* Primop `__currentSystem' to return the current platform identifier.Eelco Dolstra
2004-10-26* Don't use ATmake / ATmatch anymore, nor the ATMatcher class.Eelco Dolstra
Instead we generate data bindings (build and match functions) for the constructors specified in `constructors.def'. In particular this removes the conversions between AFuns and strings, and Nix expression evaluation now seems 3 to 4 times faster.
2004-10-26* String/path concatenation operator (`+').Eelco Dolstra