added parser and eval stub

src/BC/Eval.hs

@@ -0,0 +1,9 @@
+module BC.Eval (eval) where
+
+import BC.Types
+
+eval :: [Value] -> Value
+eval [x@(BInt _)] = x
+eval [(BOp  x)] = BErr ("operation " ++ x ++ " requires arguments")
+eval (x:xy) = x
+eval [] = BOp ""