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112 commits

Author SHA1 Message Date
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