NamedFunctions.hs

makeList :: IORef Env -> [Expression] -> IO Value
makeList env elemExprs = do
    elems <- traverse (eval env) elemExprs
    ListValue <$> newIORef elems

makeFunction :: IORef Env -> [String] -> Block -> IO Value
makeFunction _ _ _ = pure . FunctionValue . const $ pure NullValue

applyFunction :: IORef Env -> Expression -> [Expression] -> IO Value
applyFunction env f args = do
    args' <- traverse (eval env) args
    (FunctionValue f') <- eval env f
    f' args'

eval :: IORef Env -> Expression -> IO Value
eval _ NullLiteral              = pure NullValue
eval _ (NumericLiteral val)     = pure $ NumericValue val
eval _ (StringLiteral val)      = pure $ StringValue val
eval e (Variable s)             = (Map.! s) . variables <$> readIORef e
eval e (Negate val)             = liftNumeric negate <$> eval e val
eval e (a :+ b)                 = liftNumeric2 (+) <$> eval e a <*> eval e b
eval e (a :- b)                 = liftNumeric2 (-) <$> eval e a <*> eval e b
eval e (a :* b)                 = liftNumeric2 (*) <$> eval e a <*> eval e b
eval e (a :/ b)                 = liftNumeric2 (/) <$> eval e a <*> eval e b
eval e (FunctionCall f args)    = applyFunction e f args
eval e (Function args body)     = makeFunction e args body
eval e (List elems)             = makeList e elems