* 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, 4 deletions

diff --git a/src/libexpr/nixexpr-ast.def b/src/libexpr/nixexpr-ast.def
index 670db1976..ab749b3db 100644
--- a/src/libexpr/nixexpr-ast.def
+++ b/src/libexpr/nixexpr-ast.def
@@ -66,7 +66,7 @@ PrimOp | int ATermBlob ATermList | Expr |
 Attrs | ATermList | Expr |
 Closed | Expr | Expr |
 Rec | ATermList ATermList | Expr |
-Bool | ATerm | Expr |
+Bool | ATermBool | Expr |
 Null | | Expr |
 
 Bind | string Expr Pos | ATerm |
@@ -76,7 +76,7 @@ Inherit | Expr ATermList Pos | ATerm |
 Scope | | Expr |
 
 VarPat | string | Pattern |
-AttrsPat | ATermList | Pattern |
+AttrsPat | ATermList ATermBool | Pattern | # bool = `...'
 AtPat | Pattern Pattern | Pattern |
 
 Formal | string DefaultValue | ATerm |
@@ -84,8 +84,8 @@ Formal | string DefaultValue | ATerm |
 DefaultValue | Expr | DefaultValue |
 NoDefaultValue | | DefaultValue |
 
-True | | ATerm |
-False | | ATerm |
+True | | ATermBool |
+False | | ATermBool |
 
 PrimOpDef | int ATermBlob | ATerm |