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38 commits

Author SHA1 Message Date
Eelco Dolstra 9279174dde * Added an experimental feature suggested by Andres: ellipses ("...")
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 14:00:44 +00:00
Eelco Dolstra 1b962fc720 * @-patterns as in Haskell. For instance, in a function definition
f = args @ {x, y, z}: ...;

  `args' refers to the argument as a whole, which is further
  pattern-matched against the attribute set pattern {x, y, z}.
2008-08-14 12:53:29 +00:00
Eelco Dolstra e818838412 * "pattern" non-terminal. 2008-08-14 10:14:34 +00:00
Eelco Dolstra efe4b690ae * Refactoring: combine functions that take an attribute set and
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.
2008-08-14 10:04:22 +00:00
Eelco Dolstra 5664b6d7ba * Removed the "valid values" feature. Nobody uses it anyway. 2008-08-11 13:36:40 +00:00
Eelco Dolstra 6d6c68c0d2 * Added a new kind of multi-line string literal delimited by two
single quotes.  Example (from NixOS):

    job = ''
      start on network-interfaces

      start script

        rm -f /var/run/opengl-driver
        ${if videoDriver == "nvidia"        
          then "ln -sf ${nvidiaDrivers} /var/run/opengl-driver"
          else if cfg.driSupport
          then "ln -sf ${mesa} /var/run/opengl-driver"
          else ""
        }

        rm -f /var/log/slim.log

      end script
    '';

  This style has two big advantages:

  - \, ' and " aren't special, only '' and ${.  So you get a lot less
    escaping in shell scripts / configuration files in Nixpkgs/NixOS.
    The delimiter '' is rare in scripts (and can usually be written as
    "").  ${ is also fairly rare.

    Other delimiters such as <<...>>, {{...}} and <|...|> were also
    considered but this one appears to have the fewest drawbacks
    (thanks Martin).

  - Indentation is intelligently stripped so that multi-line strings
    can follow the nesting structure of the containing Nix
    expression.  E.g. in the example above 6 spaces are stripped from
    the start of each line.  This prevents unnecessary indentation in
    generated files (which sometimes even breaks things).

  See tests/lang/eval-okay-ind-string.nix for some examples.
2007-11-30 16:48:45 +00:00
Eelco Dolstra d71cc503a6 * Don't allocate input files on the stack. 2007-08-07 15:00:13 +00:00
Eelco Dolstra ca00aa1171 * Allow empty argument lists in function definitions (e.g., `{}:
bla').  Also allow trailing commas (`{x, y,}: ...') as a unintented
  consequence.  Hopefully the reduce/reduce conflict won't cause any
  problems.
2007-05-15 12:14:37 +00:00
Eelco Dolstra 71ceb1c161 * Handle multiple indirect symlinks when loading a Nix expression. 2007-01-15 14:50:25 +00:00
Eelco Dolstra 9c9cdb06d0 * Remove SwitchToOriginalUser, we're not going to need it anymore. 2006-12-02 14:34:14 +00:00
Eelco Dolstra d7efd76394 * Big cleanup of the semantics of paths, strings, contexts, string
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'.)
2006-10-16 15:55:34 +00:00
Eelco Dolstra 7d4567f2cc * Removed URIs from the evaluator (NIX-66). They are now just another
kind of notation for strings.
2006-10-11 21:59:33 +00:00
Eelco Dolstra ac19b333b3 * Finally, a real "let" syntax: `let x = ...; ... z = ...; in ...'. 2006-10-02 15:52:44 +00:00
Eelco Dolstra 7581cfdee4 * Hack for Bison 2.3 compatability. 2006-10-02 14:43:15 +00:00
Eelco Dolstra 4be5443882 * Remove unnecessary inclusions of aterm2.h. 2006-09-04 22:08:40 +00:00
Eelco Dolstra e3ce954582 * Compile the lexer as C++ code. Remove all the redundant C/C++
marshalling code.
2006-09-04 21:36:15 +00:00
Eelco Dolstra 75068e7d75 * Use a proper namespace.
* Optimise header file usage a bit.
* Compile the parser as C++.
2006-09-04 21:06:23 +00:00
Eelco Dolstra f4c5531d92 * New language feature: domain checks, which check whether a function
argument has a valid value, i.e., is in a certain domain.  E.g.,

    { foo : [true false]
    , bar : ["a" "b" "c"]
    }: ...

  This previously could be done using assertions, but domain checks
  will allow the buildfarm to automatically extract the configuration
  space from functions.
2006-07-24 16:35:34 +00:00
Eelco Dolstra 57751fdb55 * Refactoring to support domain checks. 2006-07-24 15:16:03 +00:00
Eelco Dolstra 0064599a27 * String interpolation. Expressions like
"--with-freetype2-library=" + freetype + "/lib"

  can now be written as

    "--with-freetype2-library=${freetype}/lib"

  An arbitrary expression can be enclosed within ${...}, not just
  identifiers.

* Escaping in string literals: \n, \r, \t interpreted as in C, any
  other character following \ is interpreted as-is.
  
* Newlines are now allowed in string literals.
2006-05-01 14:01:47 +00:00
Eelco Dolstra 2d2e28d02c * Override YYMALLOC and YYFREE so that we can call AT[un]protectMemory
on the Bison parse stack.  Otherwise, a garbage collect during
  parsing could lead to a crash.
2006-02-13 13:09:23 +00:00
Eelco Dolstra ed1db42915 * List concatenation must be right-associative for efficiency. 2005-09-14 11:41:59 +00:00
Eelco Dolstra 991a130b1e * Added a list concatenation operator:
[1 2 3] ++ [4 5 6] => [1 2 3 4 5 6]
2005-07-25 15:05:34 +00:00
Eelco Dolstra cb7ccb528b * string2ATerm -> overloaded toATerm. 2004-11-03 18:12:03 +00:00
Eelco Dolstra a69534fc21 * Drop ATmake / ATMatcher also in handling store expressions. 2004-10-29 11:22:49 +00:00
Eelco Dolstra 5fe9222b36 * Don't use ATmake / ATmatch anymore, nor the ATMatcher class.
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 22:54:26 +00:00
Eelco Dolstra 9fa07b376d * String/path concatenation operator (`+'). 2004-10-26 17:01:35 +00:00
Eelco Dolstra 37d7abd694 * New language feature: with expressions.
The expression `with E1; E2' evaluates to E2 with all bindings in
  the attribute set E1 substituted.  E.g.,

    with {x = 123;}; x

  evaluates to 123.  That is, the attribute set E1 is in scope in E2.

  This is particularly useful when importing files containing lots
  definitions.  E.g., instead of

    let {
      inherit (import ./foo.nix) a b c d e f;

      body = ... a ... f ...;
    }

  we can now say

    with import ./foo.nix;

    ... a ... f ...

  I.e., we don't have to say what variables should be brought into scope.
2004-10-25 16:54:56 +00:00
Eelco Dolstra 59b94ee18a * When something goes wrong in the evaluation of a Nix expression,
print a nice backtrace of the stack, rather than vomiting a gigantic
  (and useless) aterm on the screen.  Example:

    error: while evaluating file `.../pkgs/system/test.nix':
    while evaluating attribute `subversion' at `.../pkgs/system/all-packages-generic.nix', line 533:
    while evaluating function at `.../pkgs/applications/version-management/subversion/default.nix', line 1:
    assertion failed at `.../pkgs/applications/version-management/subversion/default.nix', line 13

  Since the Nix expression language is lazy, the trace may be
  misleading.  The purpose is to provide a hint as to the location of
  the problem.
2004-04-05 22:27:41 +00:00
Eelco Dolstra ac4d39f9db * Added an operator `?' to test for attribute existence, e.g.,
`attrs ? x' yields true iff `attrs' has an attribute named `x'.
2004-03-28 21:15:01 +00:00
Eelco Dolstra f958bcdf1f * Added an operator `~' to select paths within a derivation. E.g.,
{stdenv, bash}: derivation {
      builder = bash ~ /bin/sh;
      args = ["-e" "-x" ./builder.sh];
      ...
    }

  Here the attribute `builder' will evaluate to, e.g.,
  `/nix/store/1234abcd...-bash-2.0.1/bin/sh'.
2004-03-28 20:58:28 +00:00
Eelco Dolstra db3e644c1c * Added plain lambdas, e.g., `let { id = x: x; const = x: y: x; }'.
`bla:' is now no longer parsed as a URL.

* Re-enabled support for the `args' attribute in derivations to
  specify command line arguments to the builder, e.g.,

    ...
    builder = /usr/bin/python;
    args = ["-c" ./builder.py];
    ...
2004-03-28 20:34:22 +00:00
Eelco Dolstra dbf547645d * Resolve an ambiguity between ifs and attribute selection, e.g., `if
b then x else y.z'.
2004-02-19 13:11:12 +00:00
Eelco Dolstra d445da7a7b * Extended the `inherit' syntax to optionally select attributes from
other attribute sets, rather than the current scope.  E.g.,
  
    {inherit (pkgs) gcc binutils;}

  is equivalent to

    {gcc = pkgs.gcc; binutils = pkgs.binutils;}

  I am not so happy about the syntax.
2004-02-04 17:23:26 +00:00
Eelco Dolstra 9d25466b34 * An attribute set update operator (//). E.g.,
{x=1; y=2; z=3;} // {y=4;}  =>  {x=1; y=4; z=3;}
2004-02-04 16:49:51 +00:00
Eelco Dolstra 1c9c0a5a46 * Added syntactic sugar to the construction of attribute sets to
`inherit' variables from the surrounding lexical scope.

  E.g.,

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      inherit stdenv libfoo;
      xyzzy = 1;
    }

  is equivalent to

    {stdenv, libfoo}: derivation {
      builder = ./bla;
      stdenv = stdenv;
      libfoo = libfoo;
      xyzzy = 1;
    }

  Note that for mutually recursive attribute set definitions (`rec
  {...}'), this also works, that is, `rec {inherit x;}' is equivalent
  to `let {fresh = x; body = rec {x = fresh;};}', *not*
  `rec {x = x}'.
2004-02-02 21:39:33 +00:00
Eelco Dolstra 619f20775d * Parser numbers again.
* Include missing files in distributions.
2004-01-30 17:06:03 +00:00
Eelco Dolstra c5baaafae6 * Replaced the SDF parser by a substantially faster Bison/Flex
parser (roughly 80x faster).

  The absolutely latest version of Bison (1.875c) is required for
  reentrant GLR support, as well as a recent version of Flex (say,
  2.5.31).  Note that most Unix distributions ship with the
  prehistoric Flex 2.5.4, which doesn't support reentrancy.
2004-01-30 15:21:42 +00:00