* 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.

src/libexpr/nixexpr.hh

@@ -13,6 +13,8 @@
    normals forms efficiently. */
 typedef ATerm Expr;
 
+typedef ATerm Pos;
+
 
 /* Mappings from ATerms to ATerms.  This is just a wrapper around
    ATerm tables. */
@@ -53,11 +55,6 @@ private:
 typedef vector<ATerm> ATermVector;
 
 
-/* Convert a string to an ATerm (i.e., a quoted nullary function
-   applicaton). */
-ATerm string2ATerm(const string & s);
-string aterm2String(ATerm t);
-
 /* Show a position. */
 string showPos(ATerm pos);