* Use a proper namespace.

* Optimise header file usage a bit.
* Compile the parser as C++.

src/libexpr/eval.cc

@@ -1,8 +1,13 @@
 #include "eval.hh"
 #include "parser.hh"
+#include "hash.hh"
+#include "util.hh"
 #include "nixexpr-ast.hh"
 
 
+namespace nix {
+    
+
 EvalState::EvalState()
     : normalForms(32768), primOps(128)
 {
@@ -271,7 +276,7 @@ Expr wrapInContext(ATermList context, Expr e)
 static ATerm concatStrings(EvalState & state, const ATermVector & args)
 {
     ATermList context = ATempty;
-    ostringstream s;
+    std::ostringstream s;
     bool isPath = false;
 
     for (ATermVector::const_iterator i = args.begin(); i != args.end(); ++i) {
@@ -666,3 +671,6 @@ void printEvalStats(EvalState & state)
     if (showStats)
         printATermMapStats();
 }
+
+ 
+}