+ FunExpr p f args fs =
+ lookup f >>= \expected ->
+ let accST = (\(s,ts,es) e->infer e >>= \(s_,et,e_)-> pure (compose s_ s,ts++[et],es++[e_])) in
+ foldM accST (zero,[],[]) args >>= \(s1, argTs, args_)->
+ fresh >>= \tv->case expected of
+ FuncType t = pure (s1, t, e)
+ _ = (let given = foldr (->>) tv argTs in
+ lift (unify expected given) >>= \s2->
+ let fReturnType = subst s2 tv in
+ foldM foldFieldSelectors fReturnType fs >>= \returnType ->
+ (case f of
+ "print" = case head argTs of
+ IntType = pure "1printint"
+ CharType = pure "1printchar"
+ BoolType = pure "1printbool"
+ ListType (CharType) = pure "1printstr"
+ t = liftT $ Left $ SanityError p ("can not print " +++ toString t)
+ _ = pure f) >>= \newF->
+ pure (compose s2 s1, returnType, FunExpr p newF args_ fs))
+
+ IntExpr _ _ = pure $ (zero, IntType, e)
+ BoolExpr _ _ = pure $ (zero, BoolType, e)
+ CharExpr _ _ = pure $ (zero, CharType, e)
+
+foldFieldSelectors :: Type FieldSelector -> Typing Type
+foldFieldSelectors (ListType t) (FieldHd) = pure t
+foldFieldSelectors t=:(ListType _) (FieldTl) = pure t
+foldFieldSelectors (TupleType (t1, _)) (FieldFst) = pure t1
+foldFieldSelectors (TupleType (_, t2)) (FieldSnd) = pure t2
+foldFieldSelectors t fs = liftT $ Left $ FieldSelectorError zero t fs