started eval

devel/compiler/Eval.hs

@@ -0,0 +1,22 @@
+module Eval where
+
+import AbsSrc
+import AbsTgt
+
+import qualified Data.Map as M
+
+eval :: Env -> Exp -> Val
+eval env e = case e of
+  ECon c -> look c
+  EStr s -> VTok s
+  ECat x y -> VCat (ev x) (ev y)
+ where 
+   look = lookCons env
+   ev = eval env
+
+data Env = Env {
+  constants :: M.Map Ident Val
+  }
+
+lookCons :: Env -> Ident -> Val
+lookCons env c = maybe undefined id $ M.lookup c $ constants env