* Use a map to lookup primops.

* Various performance improvements in the evaluator.
* Do not link against unused (and missing!) libraries (-lsglr, etc.).

src/libexpr/primops.hh

@@ -8,7 +8,7 @@
    argument. */ 
 Expr primImport(EvalState & state, Expr arg);
 
-/* Construct (as a unobservable) side effect) a Nix derivation
+/* Construct (as a unobservable side effect) a Nix derivation
    expression that performs the derivation described by the argument
    set.  Returns the original set extended with the following
    attributes: `outPath' containing the primary output path of the
@@ -24,6 +24,10 @@ Expr primBaseNameOf(EvalState & state, Expr arg);
 /* Convert the argument (which can be a path or a uri) to a string. */
 Expr primToString(EvalState & state, Expr arg);
 
+/* Boolean constructors. */
+Expr primTrue(EvalState & state);
+Expr primFalse(EvalState & state);
+
 /* Return the null value. */
 Expr primNull(EvalState & state);