Move primop docs inline

This makes them available to 'nix repl'.

2 files changed, 1235 insertions, 118 deletions

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 902a37e6b..78892053a 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -275,6 +275,16 @@ static void prim_typeOf(EvalState & state, const Pos & pos, Value * * args, Valu
     mkString(v, state.symbols.create(t));
 }
 
+static RegisterPrimOp primop_typeOf({
+    .name = "__typeOf",
+    .args = {"e"},
+    .doc = R"(
+      Return a string representing the type of the value *e*, namely
+      `"int"`, `"bool"`, `"string"`, `"path"`, `"null"`, `"set"`,
+      `"list"`, `"lambda"` or `"float"`.
+    )",
+    .fun = prim_typeOf,
+});
 
 /* Determine whether the argument is the null value. */
 static void prim_isNull(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -283,6 +293,18 @@ static void prim_isNull(EvalState & state, const Pos & pos, Value * * args, Valu
     mkBool(v, args[0]->type == tNull);
 }
 
+static RegisterPrimOp primop_isNull({
+    .name = "isNull",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to `null`, and `false` otherwise.
+
+      > **Warning**
+      > 
+      > This function is *deprecated*; just write `e == null` instead.
+    )",
+    .fun = prim_isNull,
+});
 
 /* Determine whether the argument is a function. */
 static void prim_isFunction(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -302,6 +324,14 @@ static void prim_isFunction(EvalState & state, const Pos & pos, Value * * args,
     mkBool(v, res);
 }
 
+static RegisterPrimOp primop_isFunction({
+    .name = "__isFunction",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a function, and `false` otherwise.
+    )",
+    .fun = prim_isFunction,
+});
 
 /* Determine whether the argument is an integer. */
 static void prim_isInt(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -310,6 +340,15 @@ static void prim_isInt(EvalState & state, const Pos & pos, Value * * args, Value
     mkBool(v, args[0]->type == tInt);
 }
 
+static RegisterPrimOp primop_isInt({
+    .name = "__isInt",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to an integer, and `false` otherwise.
+    )",
+    .fun = prim_isInt,
+});
+
 /* Determine whether the argument is a float. */
 static void prim_isFloat(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -317,6 +356,15 @@ static void prim_isFloat(EvalState & state, const Pos & pos, Value * * args, Val
     mkBool(v, args[0]->type == tFloat);
 }
 
+static RegisterPrimOp primop_isFloat({
+    .name = "__isFloat",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a float, and `false` otherwise.
+    )",
+    .fun = prim_isFloat,
+});
+
 /* Determine whether the argument is a string. */
 static void prim_isString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -324,6 +372,14 @@ static void prim_isString(EvalState & state, const Pos & pos, Value * * args, Va
     mkBool(v, args[0]->type == tString);
 }
 
+static RegisterPrimOp primop_isString({
+    .name = "__isString",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a string, and `false` otherwise.
+    )",
+    .fun = prim_isString,
+});
 
 /* Determine whether the argument is a Boolean. */
 static void prim_isBool(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -332,6 +388,15 @@ static void prim_isBool(EvalState & state, const Pos & pos, Value * * args, Valu
     mkBool(v, args[0]->type == tBool);
 }
 
+static RegisterPrimOp primop_isBool({
+    .name = "__isBool",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a bool, and `false` otherwise.
+    )",
+    .fun = prim_isBool,
+});
+
 /* Determine whether the argument is a path. */
 static void prim_isPath(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -339,6 +404,15 @@ static void prim_isPath(EvalState & state, const Pos & pos, Value * * args, Valu
     mkBool(v, args[0]->type == tPath);
 }
 
+static RegisterPrimOp primop_isPath({
+    .name = "__isPath",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a path, and `false` otherwise.
+    )",
+    .fun = prim_isPath,
+});
+
 struct CompareValues
 {
     bool operator () (const Value * v1, const Value * v2) const
@@ -459,14 +533,23 @@ static RegisterPrimOp primop_abort({
     }
 });
 
-
-static void prim_throw(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-    throw ThrownError(s);
-}
-
+static RegisterPrimOp primop_throw({
+    .name = "throw",
+    .args = {"s"},
+    .doc = R"(
+      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`).
+    )",
+    .fun = [](EvalState & state, const Pos & pos, Value * * args, Value & v)
+    {
+      PathSet context;
+      string s = state.coerceToString(pos, *args[0], context);
+      throw ThrownError(s);
+    }
+});
 
 static void prim_addErrorContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -497,6 +580,22 @@ static void prim_tryEval(EvalState & state, const Pos & pos, Value * * args, Val
     v.attrs->sort();
 }
 
+static RegisterPrimOp primop_tryEval({
+    .name = "__tryEval",
+    .args = {"e"},
+    .doc = R"(
+      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`.
+    )",
+    .fun = prim_tryEval,
+});
 
 /* Return an environment variable.  Use with care. */
 static void prim_getEnv(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -505,6 +604,22 @@ static void prim_getEnv(EvalState & state, const Pos & pos, Value * * args, Valu
     mkString(v, evalSettings.restrictEval || evalSettings.pureEval ? "" : getEnv(name).value_or(""));
 }
 
+static RegisterPrimOp primop_getEnv({
+    .name = "__getEnv",
+    .args = {"s"},
+    .doc = R"(
+      `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.)
+    )",
+    .fun = prim_getEnv,
+});
 
 /* Evaluate the first argument, then return the second argument. */
 static void prim_seq(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -514,6 +629,15 @@ static void prim_seq(EvalState & state, const Pos & pos, Value * * args, Value &
     v = *args[1];
 }
 
+static RegisterPrimOp primop_seq({
+    .name = "__seq",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Evaluate *e1*, then evaluate and return *e2*. This ensures that a
+      computation is strict in the value of *e1*.
+    )",
+    .fun = prim_seq,
+});
 
 /* Evaluate the first argument deeply (i.e. recursing into lists and
    attrsets), then return the second argument. */
@@ -524,6 +648,16 @@ static void prim_deepSeq(EvalState & state, const Pos & pos, Value * * args, Val
     v = *args[1];
 }
 
+static RegisterPrimOp primop_deepSeq({
+    .name = "__deepSeq",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_deepSeq,
+});
 
 /* Evaluate the first expression and print it on standard error.  Then
    return the second expression.  Useful for debugging. */
@@ -538,6 +672,17 @@ static void prim_trace(EvalState & state, const Pos & pos, Value * * args, Value
     v = *args[1];
 }
 
+static RegisterPrimOp primop_trace({
+    .name = "__trace",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Evaluate *e1* and print its abstract syntax representation on
+      standard error. Then return *e2*. This function is useful for
+      debugging.
+    )",
+    .fun = prim_trace,
+});
+
 
 /*************************************************************
  * Derivations
@@ -879,6 +1024,17 @@ static void prim_placeholder(EvalState & state, const Pos & pos, Value * * args,
     mkString(v, hashPlaceholder(state.forceStringNoCtx(*args[0], pos)));
 }
 
+static RegisterPrimOp primop_placeholder({
+    .name = "placeholder",
+    .args = {"output"},
+    .doc = R"(
+      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"`.
+    )",
+    .fun = prim_placeholder,
+});
+
 
 /*************************************************************
  * Paths
@@ -893,6 +1049,15 @@ static void prim_toPath(EvalState & state, const Pos & pos, Value * * args, Valu
     mkString(v, canonPath(path), context);
 }
 
+static RegisterPrimOp primop_toPath({
+    .name = "__toPath",
+    .args = {"s"},
+    .doc = R"(
+      DEPRECATED. Use `/. + "/path"` to convert a string into an absolute
+      path. For relative paths, use `./. + "/path"`.
+    )",
+    .fun = prim_toPath,
+});
 
 /* Allow a valid store path to be used in an expression.  This is
    useful in some generated expressions such as in nix-push, which
@@ -904,6 +1069,9 @@ static void prim_toPath(EvalState & state, const Pos & pos, Value * * args, Valu
    corner cases. */
 static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
+    if (evalSettings.pureEval)
+        throw EvalError("builtins.storePath' is not allowed in pure evaluation mode");
+
     PathSet context;
     Path path = state.checkSourcePath(state.coerceToPath(pos, *args[0], context));
     /* Resolve symlinks in ‘path’, unless ‘path’ itself is a symlink
@@ -949,6 +1117,15 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
     }
 }
 
+static RegisterPrimOp primop_pathExists({
+    .name = "__pathExists",
+    .args = {"path"},
+    .doc = R"(
+      Return `true` if the path *path* exists at evaluation time, and
+      `false` otherwise.
+    )",
+    .fun = prim_pathExists,
+});
 
 /* Return the base name of the given string, i.e., everything
    following the last slash. */
@@ -958,6 +1135,16 @@ static void prim_baseNameOf(EvalState & state, const Pos & pos, Value * * args,
     mkString(v, baseNameOf(state.coerceToString(pos, *args[0], context, false, false)), context);
 }
 
+static RegisterPrimOp primop_baseNameOf({
+    .name = "baseNameOf",
+    .args = {"s"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_baseNameOf,
+});
 
 /* Return the directory of the given path, i.e., everything before the
    last slash.  Return either a path or a string depending on the type
@@ -969,6 +1156,16 @@ static void prim_dirOf(EvalState & state, const Pos & pos, Value * * args, Value
     if (args[0]->type == tPath) mkPath(v, dir.c_str()); else mkString(v, dir, context);
 }
 
+static RegisterPrimOp primop_dirOf({
+    .name = "dirOf",
+    .args = {"s"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_dirOf,
+});
 
 /* Return the contents of a file as a string. */
 static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -989,6 +1186,14 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     mkString(v, s.c_str());
 }
 
+static RegisterPrimOp primop_readFile({
+    .name = "__readFile",
+    .args = {"path"},
+    .doc = R"(
+      Return the contents of the file *path* as a string.
+    )",
+    .fun = prim_readFile,
+});
 
 /* Find a file in the Nix search path. Used to implement <x> paths,
    which are desugared to 'findFile __nixPath "x"'. */
@@ -1051,6 +1256,17 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
     mkString(v, hashFile(*ht, state.checkSourcePath(p)).to_string(Base16, false), context);
 }
 
+static RegisterPrimOp primop_hashFile({
+    .name = "__hashFile",
+    .args = {"type", "p"},
+    .doc = R"(
+      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"`.
+    )",
+    .fun = prim_hashFile,
+});
+
 /* Read a directory (without . or ..) */
 static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1082,6 +1298,25 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
     v.attrs->sort();
 }
 
+static RegisterPrimOp primop_readDir({
+    .name = "__readDir",
+    .args = {"path"},
+    .doc = R"(
+      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
+
+      ```nix
+      { B = "regular"; C = "directory"; }
+      ```
+
+      The possible values for the file type are `"regular"`,
+      `"directory"`, `"symlink"` and `"unknown"`.
+    )",
+    .fun = prim_readDir,
+});
+
 
 /*************************************************************
  * Creating files
@@ -1099,6 +1334,102 @@ static void prim_toXML(EvalState & state, const Pos & pos, Value * * args, Value
     mkString(v, out.str(), context);
 }
 
+static RegisterPrimOp primop_toXML({
+    .name = "__toXML",
+    .args = {"e"},
+    .doc = R"(
+      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:
+
+      ```nix
+      { stdenv, fetchurl, libxslt, jira, uberwiki }:
+
+      stdenv.mkDerivation (rec {
+        name = "web-server";
+
+        buildInputs = [ libxslt ];
+
+        builder = builtins.toFile "builder.sh" "
+          source $stdenv/setup
+          mkdir $out
+          echo "$servlets" | xsltproc ${stylesheet} - > $out/server-conf.xml ①
+        ";
+
+        stylesheet = builtins.toFile "stylesheet.xsl" ②
+         "<?xml version='1.0' encoding='UTF-8'?>
+          <xsl:stylesheet xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
+            <xsl:template match='/'>
+              <Configure>
+                <xsl:for-each select='/expr/list/attrs'>
+                  <Call name='addWebApplication'>
+                    <Arg><xsl:value-of select=\"attr[@name = 'path']/string/@value\" /></Arg>
+                    <Arg><xsl:value-of select=\"attr[@name = 'war']/path/@value\" /></Arg>
+                  </Call>
+                </xsl:for-each>
+              </Configure>
+            </xsl:template>
+          </xsl:stylesheet>
+        ";
+
+        servlets = builtins.toXML [ ③
+          { path = "/bugtracker"; war = jira + "/lib/atlassian-jira.war"; }
+          { path = "/wiki"; war = uberwiki + "/uberwiki.war"; }
+        ];
+      })
+      ```
+
+      The builder is supposed to generate the configuration file for a
+      [Jetty servlet container](http://jetty.mortbay.org/). 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
+      (①). 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:
+
+      ```xml
+      <?xml version='1.0' encoding='utf-8'?>
+      <expr>
+        <list>
+          <attrs>
+            <attr name="path">
+              <string value="/bugtracker" />
+            </attr>
+            <attr name="war">
+              <path value="/nix/store/d1jh9pasa7k2...-jira/lib/atlassian-jira.war" />
+            </attr>
+          </attrs>
+          <attrs>
+            <attr name="path">
+              <string value="/wiki" />
+            </attr>
+            <attr name="war">
+              <path value="/nix/store/y6423b1yi4sx...-uberwiki/uberwiki.war" />
+            </attr>
+          </attrs>
+        </list>
+      </expr>
+      ```
+
+      Note that we used 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}`.
+    )",
+    .fun = prim_toXML,
+});
 
 /* Convert the argument (which can be any Nix expression) to a JSON
    string.  Not all Nix expressions can be sensibly or completely
@@ -1111,6 +1442,19 @@ static void prim_toJSON(EvalState & state, const Pos & pos, Value * * args, Valu
     mkString(v, out.str(), context);
 }
 
+static RegisterPrimOp primop_toJSON({
+    .name = "__toJSON",
+    .args = {"e"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_toJSON,
+});
 
 /* Parse a JSON string to a value. */
 static void prim_fromJSON(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1119,6 +1463,20 @@ static void prim_fromJSON(EvalState & state, const Pos & pos, Value * * args, Va
     parseJSON(state, s, v);
 }
 
+static RegisterPrimOp primop_fromJSON({
+    .name = "__fromJSON",
+    .args = {"e"},
+    .doc = R"(
+      Convert a JSON string to a Nix value. For example,
+
+      ```nix
+      builtins.fromJSON ''{"x": [1, 2, 3], "y": null}''
+      ```
+
+      returns the value `{ x = [ 1 2 3 ]; y = null; }`.
+    )",
+    .fun = prim_fromJSON,
+});
 
 /* Store a string in the Nix store as a source file that can be used
    as an input by derivations. */
@@ -1153,6 +1511,83 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
     mkString(v, storePath, {storePath});
 }
 
+static RegisterPrimOp primop_toFile({
+    .name = "__toFile",
+    .args = {"name", "s"},
+    .doc = R"(
+      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 the
+      [Nix expression for GNU Hello](expression-syntax.md) and its
+      [build script](build-script.md) into one file:
+
+      ```nix
+      { 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.,
+
+      ```nix
+      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](language-values.md), 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:
+
+      ```nix
+      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.
+    )",
+    .fun = prim_toFile,
+});
 
 static void addPath(EvalState & state, const Pos & pos, const string & name, const Path & path_,
     Value * filterFun, FileIngestionMethod method, const std::optional<Hash> expectedHash, Value & v)
@@ -1223,6 +1658,48 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
     addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v);
 }
 
+static RegisterPrimOp primop_filterSource({
+    .name = "__filterSource",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      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.
+
+      ```nix
+      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:
+
+      ```nix
+      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.
+    )",
+    .fun = prim_filterSource,
+});
+
 static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceAttrs(*args[0], pos);
@@ -1268,6 +1745,41 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     addPath(state, pos, name, path, filterFun, method, expectedHash, v);
 }
 
+static RegisterPrimOp primop_path({
+    .name = "__path",
+    .args = {"args"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_path,
+});
+
 
 /*************************************************************
  * Sets
@@ -1290,6 +1802,16 @@ static void prim_attrNames(EvalState & state, const Pos & pos, Value * * args, V
               [](Value * v1, Value * v2) { return strcmp(v1->string.s, v2->string.s) < 0; });
 }
 
+static RegisterPrimOp primop_attrNames({
+    .name = "__attrNames",
+    .args = {"set"},
+    .doc = R"(
+      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" ]`.
+    )",
+    .fun = prim_attrNames,
+});
 
 /* Return the values of the attributes in a set as a list, in the same
    order as attrNames. */
@@ -1310,6 +1832,15 @@ static void prim_attrValues(EvalState & state, const Pos & pos, Value * * args,
         v.listElems()[i] = ((Attr *) v.listElems()[i])->value;
 }
 
+static RegisterPrimOp primop_attrValues({
+    .name = "__attrValues",
+    .args = {"set"},
+    .doc = R"(
+      Return the values of the attributes in the set *set* in the order
+      corresponding to the sorted attribute names.
+    )",
+    .fun = prim_attrValues,
+});
 
 /* Dynamic version of the `.' operator. */
 void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1329,9 +1860,20 @@ void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
     v = *i->value;
 }
 
+static RegisterPrimOp primop_getAttr({
+    .name = "__getAttr",
+    .args = {"s", "set"},
+    .doc = R"(
+      `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.
+    )",
+    .fun = prim_getAttr,
+});
 
 /* Return position information of the specified attribute. */
-void prim_unsafeGetAttrPos(EvalState & state, const Pos & pos, Value * * args, Value & v)
+static void prim_unsafeGetAttrPos(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     string attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
@@ -1342,7 +1884,6 @@ void prim_unsafeGetAttrPos(EvalState & state, const Pos & pos, Value * * args, V
         state.mkPos(v, i->pos);
 }
 
-
 /* Dynamic version of the `?' operator. */
 static void prim_hasAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1351,6 +1892,16 @@ static void prim_hasAttr(EvalState & state, const Pos & pos, Value * * args, Val
     mkBool(v, args[1]->attrs->find(state.symbols.create(attr)) != args[1]->attrs->end());
 }
 
+static RegisterPrimOp primop_hasAttr({
+    .name = "__hasAttr",
+    .args = {"s", "set"},
+    .doc = R"(
+      `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.
+    )",
+    .fun = prim_hasAttr,
+});
 
 /* Determine whether the argument is a set. */
 static void prim_isAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1359,6 +1910,14 @@ static void prim_isAttrs(EvalState & state, const Pos & pos, Value * * args, Val
     mkBool(v, args[0]->type == tAttrs);
 }
 
+static RegisterPrimOp primop_isAttrs({
+    .name = "__isAttrs",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a set, and `false` otherwise.
+    )",
+    .fun = prim_isAttrs,
+});
 
 static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1382,6 +1941,21 @@ static void prim_removeAttrs(EvalState & state, const Pos & pos, Value * * args,
     }
 }
 
+static RegisterPrimOp primop_removeAttrs({
+    .name = "removeAttrs",
+    .args = {"set", "list"},
+    .doc = R"(
+      Remove the attributes listed in *list* from *set*. The attributes
+      don’t have to exist in *set*. For instance,
+
+      ```nix
+      removeAttrs { x = 1; y = 2; z = 3; } [ "a" "x" "z" ]
+      ```
+
+      evaluates to `{ y = 2; }`.
+    )",
+    .fun = prim_removeAttrs,
+});
 
 /* Builds a set from a list specifying (name, value) pairs.  To be
    precise, a list [{name = "name1"; value = value1;} ... {name =
@@ -1423,6 +1997,30 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
     v.attrs->sort();
 }
 
+static RegisterPrimOp primop_listToAttrs({
+    .name = "__listToAttrs",
+    .args = {"e"},
+    .doc = R"(
+      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:
+
+      ```nix
+      builtins.listToAttrs
+        [ { name = "foo"; value = 123; }
+          { name = "bar"; value = 456; }
+        ]
+      ```
+
+      evaluates to
+
+      ```nix
+      { foo = 123; bar = 456; }
+      ```
+    )",
+    .fun = prim_listToAttrs,
+});
 
 /* Return the right-biased intersection of two sets as1 and as2,
    i.e. a set that contains every attribute from as2 that is also a
@@ -1441,6 +2039,15 @@ static void prim_intersectAttrs(EvalState & state, const Pos & pos, Value * * ar
     }
 }
 
+static RegisterPrimOp primop_intersectAttrs({
+    .name = "__intersectAttrs",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return a set consisting of the attributes in the set *e2* that also
+      exist in the set *e1*.
+    )",
+    .fun = prim_intersectAttrs,
+});
 
 /* Collect each attribute named `attr' from a list of attribute sets.
    Sets that don't contain the named attribute are ignored.
@@ -1470,7 +2077,6 @@ static void prim_catAttrs(EvalState & state, const Pos & pos, Value * * args, Va
         v.listElems()[n] = res[n];
 }
 
-
 /* 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,
@@ -1508,6 +2114,22 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
     v.attrs->sort();
 }
 
+static RegisterPrimOp primop_functionArgs({
+    .name = "__functionArgs",
+    .args = {"f"},
+    .doc = R"(
+      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:
+      ...) = { }`.
+    )",
+    .fun = prim_functionArgs,
+});
 
 /* Apply a function to every element of an attribute set. */
 static void prim_mapAttrs(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1526,7 +2148,6 @@ static void prim_mapAttrs(EvalState & state, const Pos & pos, Value * * args, Va
 }
 
 
-
 /*************************************************************
  * Lists
  *************************************************************/
@@ -1539,6 +2160,14 @@ static void prim_isList(EvalState & state, const Pos & pos, Value * * args, Valu
     mkBool(v, args[0]->isList());
 }
 
+static RegisterPrimOp primop_isList({
+    .name = "__isList",
+    .args = {"e"},
+    .doc = R"(
+      Return `true` if *e* evaluates to a list, and `false` otherwise.
+    )",
+    .fun = prim_isList,
+});
 
 static void elemAt(EvalState & state, const Pos & pos, Value & list, int n, Value & v)
 {
@@ -1552,13 +2181,21 @@ static void elemAt(EvalState & state, const Pos & pos, Value & list, int n, Valu
     v = *list.listElems()[n];
 }
 
-
 /* Return the n-1'th element of a list. */
 static void prim_elemAt(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     elemAt(state, pos, *args[0], state.forceInt(*args[1], pos), v);
 }
 
+static RegisterPrimOp primop_elemAt({
+    .name = "__elemAt",
+    .args = {"xs", "n"},
+    .doc = R"(
+      Return element *n* from the list *xs*. Elements are counted starting
+      from 0. A fatal error occurs if the index is out of bounds.
+    )",
+    .fun = prim_elemAt,
+});
 
 /* Return the first element of a list. */
 static void prim_head(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1566,6 +2203,16 @@ static void prim_head(EvalState & state, const Pos & pos, Value * * args, Value
     elemAt(state, pos, *args[0], 0, v);
 }
 
+static RegisterPrimOp primop_head({
+    .name = "__head",
+    .args = {"list"},
+    .doc = R"(
+      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 `[]`.
+    )",
+    .fun = prim_head,
+});
 
 /* Return a list consisting of everything but the first element of
    a list.  Warning: this function takes O(n) time, so you probably
@@ -1584,6 +2231,21 @@ static void prim_tail(EvalState & state, const Pos & pos, Value * * args, Value
         v.listElems()[n] = args[0]->listElems()[n + 1];
 }
 
+static RegisterPrimOp primop_tail({
+    .name = "__tail",
+    .args = {"list"},
+    .doc = R"(
+      Return the second to last elements of a list; abort evaluation if
+      the argument isn’t a list or is an empty list.
+
+      > **Warning**
+      > 
+      > This function should generally be avoided since it's inefficient:
+      > unlike Haskell's `tail`, it takes O(n) time, so recursing over a
+      > list by repeatedly calling `tail` takes O(n^2) time.
+    )",
+    .fun = prim_tail,
+});
 
 /* Apply a function to every element of a list. */
 static void prim_map(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1597,6 +2259,21 @@ static void prim_map(EvalState & state, const Pos & pos, Value * * args, Value &
             *args[0], *args[1]->listElems()[n]);
 }
 
+static RegisterPrimOp primop_map({
+    .name = "map",
+    .args = {"f", "list"},
+    .doc = R"(
+      Apply the function *f* to each element in the list *list*. For
+      example,
+
+      ```nix
+      map (x: "foo" + x) [ "bar" "bla" "abc" ]
+      ```
+
+      evaluates to `[ "foobar" "foobla" "fooabc" ]`.
+    )",
+    .fun = prim_map,
+});
 
 /* Filter a list using a predicate; that is, return a list containing
    every element from the list for which the predicate function
@@ -1628,6 +2305,15 @@ static void prim_filter(EvalState & state, const Pos & pos, Value * * args, Valu
     }
 }
 
+static RegisterPrimOp primop_filter({
+    .name = "__filter",
+    .args = {"f", "list"},
+    .doc = R"(
+      Return a list consisting of the elements of *list* for which the
+      function *f* returns `true`.
+    )",
+    .fun = prim_filter,
+});
 
 /* Return true if a list contains a given element. */
 static void prim_elem(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1642,6 +2328,15 @@ static void prim_elem(EvalState & state, const Pos & pos, Value * * args, Value
     mkBool(v, res);
 }
 
+static RegisterPrimOp primop_elem({
+    .name = "__elem",
+    .args = {"x", "xs"},
+    .doc = R"(
+      Return `true` if a value equal to *x* occurs in the list *xs*, and
+      `false` otherwise.
+    )",
+    .fun = prim_elem,
+});
 
 /* Concatenate a list of lists. */
 static void prim_concatLists(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1650,6 +2345,14 @@ static void prim_concatLists(EvalState & state, const Pos & pos, Value * * args,
     state.concatLists(v, args[0]->listSize(), args[0]->listElems(), pos);
 }
 
+static RegisterPrimOp primop_concatLists({
+    .name = "__concatLists",
+    .args = {"lists"},
+    .doc = R"(
+      Concatenate a list of lists into a single list.
+    )",
+    .fun = prim_concatLists,
+});
 
 /* Return the length of a list.  This is an O(1) time operation. */
 static void prim_length(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1658,6 +2361,14 @@ static void prim_length(EvalState & state, const Pos & pos, Value * * args, Valu
     mkInt(v, args[0]->listSize());
 }
 
+static RegisterPrimOp primop_length({
+    .name = "__length",
+    .args = {"e"},
+    .doc = R"(
+      Return the length of the list *e*.
+    )",
+    .fun = prim_length,
+});
 
 /* Reduce a list by applying a binary operator, from left to
    right. The operator is applied strictly. */
@@ -1682,6 +2393,18 @@ static void prim_foldlStrict(EvalState & state, const Pos & pos, Value * * args,
     }
 }
 
+static RegisterPrimOp primop_foldlStrict({
+    .name = "__foldl'",
+    .args = {"op", "nul", "list"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_foldlStrict,
+});
 
 static void anyOrAll(bool any, EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1707,12 +2430,30 @@ static void prim_any(EvalState & state, const Pos & pos, Value * * args, Value &
     anyOrAll(true, state, pos, args, v);
 }
 
+static RegisterPrimOp primop_any({
+    .name = "__any",
+    .args = {"pred", "list"},
+    .doc = R"(
+      Return `true` if the function *pred* returns `true` for at least one
+      element of *list*, and `false` otherwise.
+    )",
+    .fun = prim_any,
+});
 
 static void prim_all(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     anyOrAll(false, state, pos, args, v);
 }
 
+static RegisterPrimOp primop_all({
+    .name = "__all",
+    .args = {"pred", "list"},
+    .doc = R"(
+      Return `true` if the function *pred* returns `true` for all elements
+      of *list*, and `false` otherwise.
+    )",
+    .fun = prim_all,
+});
 
 static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1733,6 +2474,21 @@ static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Val
     }
 }
 
+static RegisterPrimOp primop_genList({
+    .name = "__genList",
+    .args = {"generator", "length"},
+    .doc = R"(
+      Generate list of size *length*, with each element *i* equal to the
+      value returned by *generator* `i`. For example,
+
+      ```nix
+      builtins.genList (x: x * x) 5
+      ```
+
+      returns the list `[ 0 1 4 9 16 ]`.
+    )",
+    .fun = prim_genList,
+});
 
 static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Value & v);
 
@@ -1768,6 +2524,26 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value
     std::stable_sort(v.listElems(), v.listElems() + len, comparator);
 }
 
+static RegisterPrimOp primop_sort({
+    .name = "__sort",
+    .args = {"comparator", "list"},
+    .doc = R"(
+      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,
+
+      ```nix
+      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.
+    )",
+    .fun = prim_sort,
+});
 
 static void prim_partition(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1851,6 +2627,14 @@ static void prim_add(EvalState & state, const Pos & pos, Value * * args, Value &
         mkInt(v, state.forceInt(*args[0], pos) + state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_add({
+    .name = "__add",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the sum of the numbers *e1* and *e2*.
+    )",
+    .fun = prim_add,
+});
 
 static void prim_sub(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1862,6 +2646,14 @@ static void prim_sub(EvalState & state, const Pos & pos, Value * * args, Value &
         mkInt(v, state.forceInt(*args[0], pos) - state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_sub({
+    .name = "__sub",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the difference between the numbers *e1* and *e2*.
+    )",
+    .fun = prim_sub,
+});
 
 static void prim_mul(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1873,6 +2665,14 @@ static void prim_mul(EvalState & state, const Pos & pos, Value * * args, Value &
         mkInt(v, state.forceInt(*args[0], pos) * state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_mul({
+    .name = "__mul",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the product of the numbers *e1* and *e2*.
+    )",
+    .fun = prim_mul,
+});
 
 static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1902,21 +2702,57 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
     }
 }
 
+static RegisterPrimOp primop_div({
+    .name = "__div",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the quotient of the numbers *e1* and *e2*.
+    )",
+    .fun = prim_div,
+});
+
 static void prim_bitAnd(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     mkInt(v, state.forceInt(*args[0], pos) & state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_bitAnd({
+    .name = "__bitAnd",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the bitwise AND of the integers *e1* and *e2*.
+    )",
+    .fun = prim_bitAnd,
+});
+
 static void prim_bitOr(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     mkInt(v, state.forceInt(*args[0], pos) | state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_bitOr({
+    .name = "__bitOr",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the bitwise OR of the integers *e1* and *e2*.
+    )",
+    .fun = prim_bitOr,
+});
+
 static void prim_bitXor(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     mkInt(v, state.forceInt(*args[0], pos) ^ state.forceInt(*args[1], pos));
 }
 
+static RegisterPrimOp primop_bitXor({
+    .name = "__bitXor",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      Return the bitwise XOR of the integers *e1* and *e2*.
+    )",
+    .fun = prim_bitXor,
+});
+
 static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceValue(*args[0], pos);
@@ -1925,6 +2761,17 @@ static void prim_lessThan(EvalState & state, const Pos & pos, Value * * args, Va
     mkBool(v, comp(args[0], args[1]));
 }
 
+static RegisterPrimOp primop_lessThan({
+    .name = "__lessThan",
+    .args = {"e1", "e2"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_lessThan,
+});
+
 
 /*************************************************************
  * String manipulation
@@ -1941,6 +2788,29 @@ static void prim_toString(EvalState & state, const Pos & pos, Value * * args, Va
     mkString(v, s, context);
 }
 
+static RegisterPrimOp primop_toString({
+    .name = "toString",
+    .args = {"e"},
+    .doc = R"(
+      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.
+    )",
+    .fun = prim_toString,
+});
 
 /* `substring start len str' returns the substring of `str' starting
    at character position `min(start, stringLength str)' inclusive and
@@ -1962,6 +2832,25 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
     mkString(v, (unsigned int) start >= s.size() ? "" : string(s, start, len), context);
 }
 
+static RegisterPrimOp primop_substring({
+    .name = "__substring",
+    .args = {"start", "len", "s"},
+    .doc = R"(
+      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,
+
+      ```nix
+      builtins.substring 0 3 "nixos"
+      ```
+
+      evaluates to `"nix"`.
+    )",
+    .fun = prim_substring,
+});
 
 static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -1970,6 +2859,15 @@ static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args
     mkInt(v, s.size());
 }
 
+static RegisterPrimOp primop_stringLength({
+    .name = "__stringLength",
+    .args = {"e"},
+    .doc = R"(
+      Return the length of the string *e*. If *e* is not a string,
+      evaluation is aborted.
+    )",
+    .fun = prim_stringLength,
+});
 
 /* Return the cryptographic hash of a string in base-16. */
 static void prim_hashString(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -1988,6 +2886,16 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
     mkString(v, hashString(*ht, s).to_string(Base16, false), context);
 }
 
+static RegisterPrimOp primop_hashString({
+    .name = "__hashString",
+    .args = {"type", "s"},
+    .doc = R"(
+      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"`.
+    )",
+    .fun = prim_hashString,
+});
 
 /* Match a regular expression against a string and return either
    ‘null’ or a list containing substring matches. */
@@ -2036,6 +2944,41 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
     }
 }
 
+static RegisterPrimOp primop_match({
+    .name = "__match",
+    .args = {"regex", "str"},
+    .doc = R"s(
+      Returns a list if the [extended POSIX regular
+      expression](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04)
+      *regex* matches *str* precisely, otherwise returns `null`. Each item
+      in the list is a regex group.
+
+      ```nix
+      builtins.match "ab" "abc"
+      ```
+
+      Evaluates to `null`.
+
+      ```nix
+      builtins.match "abc" "abc"
+      ```
+
+      Evaluates to `[ ]`.
+
+      ```nix
+      builtins.match "a(b)(c)" "abc"
+      ```
+
+      Evaluates to `[ "b" "c" ]`.
+
+      ```nix
+      builtins.match "[[:space:]]+([[:upper:]]+)[[:space:]]+" "  FOO   "
+      ```
+
+      Evaluates to `[ "foo" ]`.
+    )s",
+    .fun = prim_match,
+});
 
 /* Split a string with a regular expression, and return a list of the
    non-matching parts interleaved by the lists of the matching groups. */
@@ -2109,8 +3052,44 @@ static void prim_split(EvalState & state, const Pos & pos, Value * * args, Value
     }
 }
 
+static RegisterPrimOp primop_split({
+    .name = "__split",
+    .args = {"regex", "str"},
+    .doc = R"s(
+      Returns a list composed of non matched strings interleaved with the
+      lists of the [extended POSIX regular
+      expression](http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04)
+      *regex* matches of *str*. Each item in the lists of matched
+      sequences is a regex group.
+
+      ```nix
+      builtins.split "(a)b" "abc"
+      ```
+
+      Evaluates to `[ "" [ "a" ] "c" ]`.
+
+      ```nix
+      builtins.split "([ac])" "abc"
+      ```
+
+      Evaluates to `[ "" [ "a" ] "b" [ "c" ] "" ]`.
+
+      ```nix
+      builtins.split "(a)|(c)" "abc"
+      ```
+
+      Evaluates to `[ "" [ "a" null ] "b" [ null "c" ] "" ]`.
 
-static void prim_concatStringSep(EvalState & state, const Pos & pos, Value * * args, Value & v)
+      ```nix
+      builtins.split "([[:upper:]]+)" "  FOO   "
+      ```
+
+      Evaluates to `[ " " [ "FOO" ] " " ]`.
+    )s",
+    .fun = prim_split,
+});
+
+static void prim_concatStringsSep(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     PathSet context;
 
@@ -2129,6 +3108,16 @@ static void prim_concatStringSep(EvalState & state, const Pos & pos, Value * * a
     mkString(v, res, context);
 }
 
+static RegisterPrimOp primop_concatStringsSep({
+    .name = "__concatStringsSep",
+    .args = {"separator", "list"},
+    .doc = R"(
+      Concatenate a list of strings with a separator between each
+      element, e.g. `concatStringsSep "/" ["usr" "local" "bin"] ==
+      "usr/local/bin"`.
+    )",
+    .fun = prim_concatStringsSep,
+});
 
 static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2188,6 +3177,22 @@ static void prim_replaceStrings(EvalState & state, const Pos & pos, Value * * ar
     mkString(v, res, context);
 }
 
+static RegisterPrimOp primop_replaceStrings({
+    .name = "__replaceStrings",
+    .args = {"from", "to", "s"},
+    .doc = R"(
+      Given string *s*, replace every occurrence of the strings in *from*
+      with the corresponding string in *to*. For example,
+
+      ```nix
+      builtins.replaceStrings ["oo" "a"] ["a" "i"] "foobar"
+      ```
+
+      evaluates to `"fabir"`.
+    )",
+    .fun = prim_replaceStrings,
+});
+
 
 /*************************************************************
  * Versions
@@ -2204,6 +3209,19 @@ static void prim_parseDrvName(EvalState & state, const Pos & pos, Value * * args
     v.attrs->sort();
 }
 
+static RegisterPrimOp primop_parseDrvName({
+    .name = "__parseDrvName",
+    .args = {"s"},
+    .doc = R"(
+      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"; }`.
+    )",
+    .fun = prim_parseDrvName,
+});
 
 static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2212,6 +3230,18 @@ static void prim_compareVersions(EvalState & state, const Pos & pos, Value * * a
     mkInt(v, compareVersions(version1, version2));
 }
 
+static RegisterPrimOp primop_compareVersions({
+    .name = "__compareVersions",
+    .args = {"s1", "s2"},
+    .doc = R"(
+      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`](../command-ref/nix-env.md#operation---upgrade).
+    )",
+    .fun = prim_compareVersions,
+});
 
 static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2232,6 +3262,17 @@ static void prim_splitVersion(EvalState & state, const Pos & pos, Value * * args
     }
 }
 
+static RegisterPrimOp primop_splitVersion({
+    .name = "__splitVersion",
+    .args = {"s"},
+    .doc = R"(
+      Split a string representing a version into its components, by the
+      same version splitting logic underlying the version comparison in
+      [`nix-env -u`](../command-ref/nix-env.md#operation---upgrade).
+    )",
+    .fun = prim_splitVersion,
+});
+
 
 /*************************************************************
  * Primop registration
@@ -2282,15 +3323,6 @@ void EvalState::createBaseEnv()
     mkNull(v);
     addConstant("null", v);
 
-    auto vThrow = addPrimOp("throw", 1, prim_throw);
-
-    auto addPurityError = [&](const std::string & name) {
-        Value * v2 = allocValue();
-        mkString(*v2, fmt("'%s' is not allowed in pure evaluation mode", name));
-        mkApp(v, *vThrow, *v2);
-        addConstant(name, v);
-    };
-
     if (!evalSettings.pureEval) {
         mkInt(v, time(0));
         addConstant("__currentTime", v);
@@ -2325,115 +3357,24 @@ void EvalState::createBaseEnv()
         addPrimOp("__importNative", 2, prim_importNative);
         addPrimOp("__exec", 1, prim_exec);
     }
-    addPrimOp("__typeOf", 1, prim_typeOf);
-    addPrimOp("isNull", 1, prim_isNull);
-    addPrimOp("__isFunction", 1, prim_isFunction);
-    addPrimOp("__isString", 1, prim_isString);
-    addPrimOp("__isInt", 1, prim_isInt);
-    addPrimOp("__isFloat", 1, prim_isFloat);
-    addPrimOp("__isBool", 1, prim_isBool);
-    addPrimOp("__isPath", 1, prim_isPath);
     addPrimOp("__genericClosure", 1, prim_genericClosure);
     addPrimOp("__addErrorContext", 2, prim_addErrorContext);
-    addPrimOp("__tryEval", 1, prim_tryEval);
-    addPrimOp("__getEnv", 1, prim_getEnv);
-
-    // Strictness
-    addPrimOp("__seq", 2, prim_seq);
-    addPrimOp("__deepSeq", 2, prim_deepSeq);
-
-    // Debugging
-    addPrimOp("__trace", 2, prim_trace);
 
     // Paths
-    addPrimOp("__toPath", 1, prim_toPath);
-    if (evalSettings.pureEval)
-        addPurityError("__storePath");
-    else
-        addPrimOp("__storePath", 1, prim_storePath);
-    addPrimOp("__pathExists", 1, prim_pathExists);
-    addPrimOp("baseNameOf", 1, prim_baseNameOf);
-    addPrimOp("dirOf", 1, prim_dirOf);
-    addPrimOp("__readFile", 1, prim_readFile);
-    addPrimOp("__readDir", 1, prim_readDir);
+    addPrimOp("__storePath", 1, prim_storePath);
     addPrimOp("__findFile", 2, prim_findFile);
-    addPrimOp("__hashFile", 2, prim_hashFile);
-
-    // Creating files
-    addPrimOp("__toXML", 1, prim_toXML);
-    addPrimOp("__toJSON", 1, prim_toJSON);
-    addPrimOp("__fromJSON", 1, prim_fromJSON);
-    addPrimOp("__toFile", 2, prim_toFile);
-    addPrimOp("__filterSource", 2, prim_filterSource);
-    addPrimOp("__path", 1, prim_path);
 
     // Sets
-    addPrimOp("__attrNames", 1, prim_attrNames);
-    addPrimOp("__attrValues", 1, prim_attrValues);
-    addPrimOp("__getAttr", 2, prim_getAttr);
     addPrimOp("__unsafeGetAttrPos", 2, prim_unsafeGetAttrPos);
-    addPrimOp("__hasAttr", 2, prim_hasAttr);
-    addPrimOp("__isAttrs", 1, prim_isAttrs);
-    addPrimOp("removeAttrs", 2, prim_removeAttrs);
-    addPrimOp("__listToAttrs", 1, prim_listToAttrs);
-    addPrimOp("__intersectAttrs", 2, prim_intersectAttrs);
     addPrimOp("__catAttrs", 2, prim_catAttrs);
-    addPrimOp("__functionArgs", 1, prim_functionArgs);
     addPrimOp("__mapAttrs", 2, prim_mapAttrs);
 
     // Lists
-    addPrimOp("__isList", 1, prim_isList);
-    addPrimOp("__elemAt", 2, prim_elemAt);
-    addPrimOp("__head", 1, prim_head);
-    addPrimOp("__tail", 1, prim_tail);
-    addPrimOp("map", 2, prim_map);
-    addPrimOp("__filter", 2, prim_filter);
-    addPrimOp("__elem", 2, prim_elem);
-    addPrimOp("__concatLists", 1, prim_concatLists);
-    addPrimOp("__length", 1, prim_length);
-    addPrimOp("__foldl'", 3, prim_foldlStrict);
-    addPrimOp("__any", 2, prim_any);
-    addPrimOp("__all", 2, prim_all);
-    addPrimOp("__genList", 2, prim_genList);
-    addPrimOp("__sort", 2, prim_sort);
     addPrimOp("__partition", 2, prim_partition);
     addPrimOp("__concatMap", 2, prim_concatMap);
 
-    // Integer arithmetic
-    addPrimOp("__add", 2, prim_add);
-    addPrimOp("__sub", 2, prim_sub);
-    addPrimOp("__mul", 2, prim_mul);
-    addPrimOp("__div", 2, prim_div);
-    addPrimOp("__bitAnd", 2, prim_bitAnd);
-    addPrimOp("__bitOr", 2, prim_bitOr);
-    addPrimOp("__bitXor", 2, prim_bitXor);
-    addPrimOp("__lessThan", 2, prim_lessThan);
-
-    // String manipulation
-    addPrimOp("toString", 1, prim_toString);
-    addPrimOp("__substring", 3, prim_substring);
-    addPrimOp("__stringLength", 1, prim_stringLength);
-    addPrimOp("__hashString", 2, prim_hashString);
-    addPrimOp("__match", 2, prim_match);
-    addPrimOp("__split", 2, prim_split);
-    addPrimOp("__concatStringsSep", 2, prim_concatStringSep);
-    addPrimOp("__replaceStrings", 3, prim_replaceStrings);
-
-    // Versions
-    addPrimOp("__parseDrvName", 1, prim_parseDrvName);
-    addPrimOp("__compareVersions", 2, prim_compareVersions);
-    addPrimOp("__splitVersion", 1, prim_splitVersion);
-
     // Derivations
     addPrimOp("derivationStrict", 1, prim_derivationStrict);
-    addPrimOp("placeholder", 1, prim_placeholder);
-
-    /* Add a wrapper around the derivation primop that computes the
-       `drvPath' and `outPath' attributes lazily. */
-    string path = canonPath(settings.nixDataDir + "/nix/corepkgs/derivation.nix", true);
-    sDerivationNix = symbols.create(path);
-    evalFile(path, v);
-    addConstant("derivation", v);
 
     /* Add a value containing the current Nix expression search path. */
     mkList(v, searchPath.size());
@@ -2458,6 +3399,13 @@ void EvalState::createBaseEnv()
                     .doc = primOp.doc,
                 });
 
+    /* Add a wrapper around the derivation primop that computes the
+       `drvPath' and `outPath' attributes lazily. */
+    string path = canonPath(settings.nixDataDir + "/nix/corepkgs/derivation.nix", true);
+    sDerivationNix = symbols.create(path);
+    evalFile(path, v);
+    addConstant("derivation", v);
+
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */
     baseEnv.values[0]->attrs->sort();
diff --git a/src/libexpr/primops/fetchTree.cc b/src/libexpr/primops/fetchTree.cc
index 0dbf4ae1d..06e8304b8 100644
--- a/src/libexpr/primops/fetchTree.cc
+++ b/src/libexpr/primops/fetchTree.cc
@@ -226,18 +226,187 @@ static void prim_fetchurl(EvalState & state, const Pos & pos, Value * * args, Va
     fetch(state, pos, args, v, "fetchurl", false, "");
 }
 
+static RegisterPrimOp primop_fetchurl({
+    .name = "__fetchurl",
+    .args = {"url"},
+    .doc = R"(
+      Download the specified URL and return the path of the downloaded
+      file. This function is not available if [restricted evaluation
+      mode](../command-ref/conf-file.md) is enabled.
+    )",
+    .fun = prim_fetchurl,
+});
+
 static void prim_fetchTarball(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     fetch(state, pos, args, v, "fetchTarball", true, "source");
 }
 
+static RegisterPrimOp primop_fetchTarball({
+    .name = "fetchTarball",
+    .args = {"args"},
+    .doc = R"(
+      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.
+
+      ```nix
+      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 `--option tarball-ttl number
+      of seconds` 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.
+
+      ```nix
+      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](../command-ref/conf-file.md) is enabled.
+    )",
+    .fun = prim_fetchTarball,
+});
+
 static void prim_fetchGit(EvalState &state, const Pos &pos, Value **args, Value &v)
 {
     fetchTree(state, pos, args, v, "git", true);
 }
 
-static RegisterPrimOp r2("__fetchurl", 1, prim_fetchurl);
-static RegisterPrimOp r3("fetchTarball", 1, prim_fetchTarball);
-static RegisterPrimOp r4("fetchGit", 1, prim_fetchGit);
+static RegisterPrimOp primop_fetchGit({
+    .name = "fetchGit",
+    .args = {"args"},
+    .doc = R"(
+      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:
+
+          ```nix
+          builtins.fetchGit {
+            url = "git@github.com:my-secret/repository.git";
+            ref = "master";
+            rev = "adab8b916a45068c044658c4158d81878f9ed1c3";
+          }
+          ```
+
+        - To fetch an arbitrary reference:
+
+          ```nix
+          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.
+
+          ```nix
+          builtins.fetchGit {
+            url = "https://github.com/nixos/nix.git";
+            rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
+            ref = "1.11-maintenance";
+          }
+          ```
+
+          > **Note**
+          > 
+          > 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.
+
+          ```nix
+          builtins.fetchGit {
+            url = "https://github.com/nixos/nix.git";
+            rev = "841fcbd04755c7a2865c51c1e2d3b045976b7452";
+          }
+          ```
+
+        - To fetch a specific tag:
+
+          ```nix
+          builtins.fetchGit {
+            url = "https://github.com/nixos/nix.git";
+            ref = "refs/tags/1.9";
+          }
+          ```
+
+        - To fetch the latest version of a remote branch:
+
+          ```nix
+          builtins.fetchGit {
+            url = "ssh://git@github.com/nixos/nix.git";
+            ref = "master";
+          }
+          ```
+
+          > **Note**
+          > 
+          > Nix will refetch the branch in accordance with
+          > the option `tarball-ttl`.
+
+          > **Note**
+          > 
+          > This behavior is disabled in *Pure evaluation mode*.
+    )",
+    .fun = prim_fetchGit,
+});
 
 }