+ Just t = restoreGamma gamma >>| updateFunType t returntype
+ >>= \tt-> pure (FunDecl p f args (Just tt) newvds newstmts)
+
+recoverType :: Type -> Env Type
+recoverType (IdType ident) = gets (\(st, r)->'Map'.get ident st)
+ >>= \mt->case mt of
+ Nothing = pure (IdType ident)
+ Just t = pure t
+recoverType (t1 ->> t2) = recoverType t1 >>= \t1`->recoverType t2
+ >>= \t2`->pure (t1` ->> t2`)
+recoverType t = pure t
+
+updateFunType :: Type Type -> Env Type
+updateFunType (t1 ->> t2) t3 = updateFunType t2 t3 >>= \t2`->pure $ t1 ->> t2`
+updateFunType t1 t2 = unify t1 t2