Haskell: add error handling and try*/catch*.

[jackhill/mal.git] / haskell / Types.hs

module Types
(MalVal (..), MalError (..), IOThrows (..), Fn (..), EnvData (..), Env,
 throwStr, throwMalVal, _get_call, _to_list,
 _func, _malfunc,
 _nil_Q, _true_Q, _false_Q, _symbol_Q, _keyword_Q,
 _list_Q, _vector_Q, _hash_map_Q, _atom_Q)
where

import Data.IORef (IORef)
import qualified Data.Map as Map
import Control.Exception as CE
import Control.Monad.Error (ErrorT, Error, noMsg, strMsg, throwError)


-- Base Mal types --
newtype Fn = Fn ([MalVal] -> IOThrows MalVal)
data MalVal = Nil
            | MalFalse
            | MalTrue
            | MalNumber   Int
            | MalString   String
            | MalSymbol   String
            | MalList     [MalVal] MalVal
            | MalVector   [MalVal] MalVal
            | MalHashMap  (Map.Map String MalVal) MalVal
            | MalAtom     (IORef MalVal) MalVal
            | Func        Fn MalVal
            | MalFunc     {fn :: Fn,
                           ast :: MalVal,
                           env :: Env,
                           params :: MalVal,
                           macro :: Bool,
                           meta :: MalVal}

_equal_Q Nil Nil = True
_equal_Q MalFalse MalFalse = True
_equal_Q MalTrue MalTrue = True
_equal_Q (MalNumber a) (MalNumber b) = a == b
_equal_Q (MalString a) (MalString b) = a == b
_equal_Q (MalSymbol a) (MalSymbol b) = a == b
_equal_Q (MalList a _) (MalList b _) = a == b
_equal_Q (MalList a _) (MalVector b _) = a == b
_equal_Q (MalVector a _) (MalList b _) = a == b
_equal_Q (MalHashMap a _) (MalHashMap b _) = a == b
_equal_Q (MalAtom a _) (MalAtom b _) = a == b
_equal_Q _ _ = False

instance Eq MalVal where
    x == y = _equal_Q x y


--- Errors/Exceptions ---

data MalError = StringError String
              | MalValError MalVal

type IOThrows = ErrorT MalError IO

instance Error MalError where
    noMsg = StringError "An error has occurred"
    strMsg = StringError

throwStr str = throwError $ StringError str
throwMalVal mv = throwError $ MalValError mv

-- Env types --
-- Note: Env functions are in Env module
data EnvData = EnvPair (Maybe Env, (Map.Map String MalVal))
type Env = IORef EnvData



----------------------------------------------------------

-- General functions --

_get_call ((Func (Fn f) _) : _) = return f
_get_call (MalFunc {fn=(Fn f)} : _) = return f
_get_call _ = throwStr "_get_call first parameter is not a function "

_to_list (MalList lst _) = return lst
_to_list (MalVector lst _) = return lst
_to_list _ = throwStr "_to_list expected a MalList or MalVector"

-- Errors

--catchAny :: IO a -> (CE.SomeException -> IO a) -> IO a
--catchAny = CE.catch

-- Functions

_func fn = Func (Fn fn) Nil
_func_meta fn meta = Func (Fn fn) meta

_malfunc ast env params fn = MalFunc {fn=(Fn fn), ast=ast,
                                      env=env, params=params,
                                      macro=False, meta=Nil}
_malfunc_meta ast env params fn meta = MalFunc {fn=(Fn fn), ast=ast,
                                                env=env, params=params,
                                                macro=False, meta=meta}

-- Scalars
_nil_Q Nil = MalTrue
_nil_Q _   = MalFalse

_true_Q MalTrue = MalTrue
_true_Q _       = MalFalse

_false_Q MalFalse = MalTrue
_false_Q _        = MalFalse

_symbol_Q (MalSymbol _) = MalTrue
_symbol_Q _             = MalFalse

_keyword_Q (MalString ('\x029e':_)) = MalTrue
_keyword_Q _                        = MalFalse

-- Lists

_list_Q (MalList _ _) = MalTrue
_list_Q _             = MalFalse

-- Vectors

_vector_Q (MalVector _ _) = MalTrue
_vector_Q _               = MalFalse

-- Hash Maps

_hash_map_Q (MalHashMap _ _) = MalTrue
_hash_map_Q _                = MalFalse

-- Atoms

_atom_Q (MalAtom _ _) = MalTrue
_atom_Q _             = MalFalse