* 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.

src/libexpr/nixexpr-ast.def

@@ -3,8 +3,7 @@ init initNixExprHelpers
 Pos | string int int | Pos |
 NoPos | | Pos |
 
-Function | ATermList Expr Pos | Expr |
-Function1 | string Expr Pos | Expr |
+Function | Pattern Expr Pos | Expr |
 Assert | Expr Expr Pos | Expr |
 With | Expr Expr Pos | Expr |
 If | Expr Expr Expr | Expr |
@@ -76,6 +75,9 @@ Inherit | Expr ATermList Pos | ATerm |
 
 Scope | | Expr |
 
+VarPat | string | Pattern |
+AttrsPat | ATermList | Pattern |
+
 Formal | string DefaultValue | ATerm |
 
 DefaultValue | Expr | DefaultValue |