* 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).

1 files changed, 4 insertions, 1 deletions

diff --git a/tests/lang/eval-okay-patterns.nix b/tests/lang/eval-okay-patterns.nix
index bcb9f3842e47..c233c406c766 100644
--- a/tests/lang/eval-okay-patterns.nix
+++ b/tests/lang/eval-okay-patterns.nix
@@ -8,9 +8,12 @@ let
 
   i = args@args2: args.x + args2.y;
 
+  j = {x, y, z, ...}: x + y + z;
+
 in
   f {x = "a"; y = "b"; z = "c";} +
   g {x = "x"; y = "y"; z = "z";} +
   h {x = "D";} +
   h {x = "D"; y = "E"; z = "F";} +
-  i {x = "g"; y = "h";}
+  i {x = "g"; y = "h";} +
+  j {x = "i"; y = "j"; z = "k"; bla = "bla"; foo = "bar";}