module Language.Scheme.Core
(
eval
, evalLisp
, evalString
, evalAndPrint
, primitiveBindings
) where
import Language.Scheme.Macro
import Language.Scheme.Numerical
import Language.Scheme.Parser
import Language.Scheme.Types
import Language.Scheme.Variables
import Control.Monad.Error
import Char
import Data.Array
import qualified Data.Map
import Maybe
import List
import IO hiding (try)
import System.Directory (doesFileExist)
import System.IO.Error
evalString :: Env -> String -> IO String
evalString env expr = runIOThrows $ liftM show $ (liftThrows $ readExpr expr) >>= macroEval env >>= (eval env (makeNullContinuation env))
evalAndPrint :: Env -> String -> IO ()
evalAndPrint env expr = evalString env expr >>= putStrLn
evalLisp :: Env -> LispVal -> IOThrowsError LispVal
evalLisp env lisp = macroEval env lisp >>= (eval env (makeNullContinuation env))
continueEval :: Env -> LispVal -> LispVal -> IOThrowsError LispVal
continueEval _
(Continuation cEnv (Just (HaskellBody func funcArgs))
(Just (Continuation cce cnc ccc _ cdynwind))
xargs _)
val = func cEnv (Continuation cce cnc ccc xargs cdynwind) val funcArgs
continueEval _ (Continuation cEnv (Just (SchemeBody cBody)) (Just cCont) extraArgs dynWind) val = do
case cBody of
[] -> do
case cCont of
Continuation nEnv ncCont nnCont _ nDynWind ->
continueEval nEnv (Continuation nEnv ncCont nnCont extraArgs nDynWind) val
_ -> return (val)
[lv] -> eval cEnv (Continuation cEnv (Just (SchemeBody [])) (Just cCont) Nothing dynWind) (lv)
(lv : lvs) -> eval cEnv (Continuation cEnv (Just (SchemeBody lvs)) (Just cCont) Nothing dynWind) (lv)
continueEval _ (Continuation cEnv Nothing (Just cCont) _ _) val = continueEval cEnv cCont val
continueEval _ (Continuation _ Nothing Nothing _ _) val = return val
continueEval _ _ _ = throwError $ Default "Internal error in continueEval"
eval :: Env -> LispVal -> LispVal -> IOThrowsError LispVal
eval env cont val@(Nil _) = continueEval env cont val
eval env cont val@(String _) = continueEval env cont val
eval env cont val@(Char _) = continueEval env cont val
eval env cont val@(Complex _) = continueEval env cont val
eval env cont val@(Float _) = continueEval env cont val
eval env cont val@(Rational _) = continueEval env cont val
eval env cont val@(Number _) = continueEval env cont val
eval env cont val@(Bool _) = continueEval env cont val
eval env cont val@(HashTable _) = continueEval env cont val
eval env cont val@(Vector _) = continueEval env cont val
eval env cont (Atom a) = continueEval env cont =<< getVar env a
eval env cont (List [Atom "quote", val]) = continueEval env cont val
eval envi cont (List [Atom "quasiquote", value]) = cpsUnquote envi cont value Nothing
where cpsUnquote :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquote e c val _ = do
case val of
List [Atom "unquote", vval] -> eval e c vval
List (_ : _) -> doCpsUnquoteList e c val
DottedList xs x -> do
doCpsUnquoteList e (makeCPSWArgs e c cpsUnquotePair $ [x] ) $ List xs
Vector vec -> do
let len = length (elems vec)
if len > 0
then doCpsUnquoteList e (makeCPS e c cpsUnquoteVector) $ List $ elems vec
else continueEval e c $ Vector $ listArray (0, 1) []
_ -> eval e c (List [Atom "quote", val])
cpsUnquotePair :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquotePair e c (List rxs) (Just [rx]) = do
cpsUnquote e (makeCPSWArgs e c cpsUnquotePairFinish $ [List rxs]) rx Nothing
cpsUnquotePair _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquotePair"
cpsUnquotePairFinish :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquotePairFinish e c rx (Just [List rxs]) = do
case rx of
List [] -> continueEval e c $ List rxs
List rxlst -> continueEval e c $ List $ rxs ++ rxlst
DottedList rxlst rxlast -> continueEval e c $ DottedList (rxs ++ rxlst) rxlast
_ -> continueEval e c $ DottedList rxs rx
cpsUnquotePairFinish _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquotePairFinish"
cpsUnquoteVector :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquoteVector e c (List vList) _ = continueEval e c (Vector $ listArray (0, (length vList 1)) vList)
cpsUnquoteVector _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquoteVector"
doCpsUnquoteList :: Env -> LispVal -> LispVal -> IOThrowsError LispVal
doCpsUnquoteList e c (List (x:xs)) = cpsUnquoteList e c x $ Just ([List xs, List []])
doCpsUnquoteList _ _ _ = throwError $ InternalError "Unexpected parameters to doCpsUnquoteList"
cpsUnquoteList :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquoteList e c val (Just ([List unEvaled, List acc])) = do
case val of
List [Atom "unquote-splicing", vvar] -> do
eval e (makeCPSWArgs e c cpsUnquoteSplicing $ [List unEvaled, List acc]) vvar
_ -> cpsUnquote e (makeCPSWArgs e c cpsUnquoteFld $ [List unEvaled, List acc]) val Nothing
cpsUnquoteList _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquoteList"
cpsUnquoteSplicing :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquoteSplicing e c val (Just ([List unEvaled, List acc])) = do
case val of
List v -> case unEvaled of
[] -> continueEval e c $ List $ acc ++ v
_ -> cpsUnquoteList e c (head unEvaled) (Just [List (tail unEvaled), List $ acc ++ v ])
_ -> throwError $ TypeMismatch "proper list" val
cpsUnquoteSplicing _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquoteSplicing"
cpsUnquoteFld :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUnquoteFld e c val (Just ([List unEvaled, List acc])) = do
case unEvaled of
[] -> continueEval e c $ List $ acc ++ [val]
_ -> cpsUnquoteList e c (head unEvaled) (Just [List (tail unEvaled), List $ acc ++ [val] ])
cpsUnquoteFld _ _ _ _ = throwError $ InternalError "Unexpected parameters to cpsUnquoteFld"
eval env cont (List [Atom "if", predic, conseq, alt]) = do
eval env (makeCPS env cont cps) (predic)
where cps :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cps e c result _ =
case (result) of
Bool False -> eval e c alt
_ -> eval e c conseq
eval env cont (List [Atom "if", predic, conseq]) =
eval env (makeCPS env cont cpsResult) predic
where cpsResult :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsResult e c result _ =
case result of
Bool True -> eval e c conseq
_ -> continueEval e c $ Nil ""
eval env cont (List (Atom "cond" : clauses)) =
if length clauses == 0
then throwError $ BadSpecialForm "No matching clause" $ String "cond"
else do
case (clauses !! 0) of
List [test, Atom "=>", expr] -> eval env (makeCPSWArgs env cont cpsAlt [test]) expr
List (Atom "else" : _) -> eval env (makeCPSWArgs env cont cpsResult clauses) $ Bool True
List (cond : _) -> eval env (makeCPSWArgs env cont cpsResult clauses) cond
badType -> throwError $ TypeMismatch "clause" badType
where
cpsResult :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsResult e cnt result (Just (c:cs)) =
case result of
Bool True -> evalCond e cnt c
_ -> eval env cnt $ List $ (Atom "cond" : cs)
cpsResult _ _ _ _ = throwError $ Default "Unexpected error in cond"
evalCond :: Env -> LispVal -> LispVal -> IOThrowsError LispVal
evalCond e c (List [_, expr]) = eval e c expr
evalCond e c (List (_ : expr)) = eval e c $ List (Atom "begin" : expr)
evalCond _ _ badForm = throwError $ BadSpecialForm "evalCond: Unrecognized special form" badForm
cpsAlt :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsAlt e c expr (Just [test]) = eval e (makeCPSWArgs e c cpsAltEvaled [expr]) test
cpsAlt _ _ _ _ = throwError $ Default "Unexpected error in cond"
cpsAltEvaled :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsAltEvaled _ c test (Just [expr]) = apply c expr [test]
cpsAltEvaled _ _ _ _ = throwError $ Default "Unexpected error in cond"
eval env cont (List (Atom "begin" : funcs)) =
if length funcs == 0
then eval env cont $ Nil ""
else if length funcs == 1
then eval env cont (head funcs)
else eval env (makeCPSWArgs env cont cpsRest $ tail funcs) (head funcs)
where cpsRest :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsRest e c _ args =
case args of
Just fArgs -> eval e c $ List (Atom "begin" : fArgs)
Nothing -> throwError $ Default "Unexpected error in begin"
eval env cont (List [Atom "set!", Atom var, form]) = do
eval env (makeCPS env cont cpsResult) form
where cpsResult :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsResult e c result _ = setVar e var result >>= continueEval e c
eval _ _ (List [Atom "set!", nonvar, _]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "set!" : args)) = throwError $ NumArgs 2 args
eval env cont (List [Atom "define", Atom var, form]) = do
eval env (makeCPS env cont cpsResult) form
where cpsResult :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsResult e c result _ = defineVar e var result >>= continueEval e c
eval env cont (List (Atom "define" : List (Atom var : fparams) : fbody )) = do
result <- (makeNormalFunc env fparams fbody >>= defineVar env var)
continueEval env cont result
eval env cont (List (Atom "define" : DottedList (Atom var : fparams) varargs : fbody)) = do
result <- (makeVarargs varargs env fparams fbody >>= defineVar env var)
continueEval env cont result
eval env cont (List (Atom "lambda" : List fparams : fbody)) = do
result <- makeNormalFunc env fparams fbody
continueEval env cont result
eval env cont (List (Atom "lambda" : DottedList fparams varargs : fbody)) = do
result <- makeVarargs varargs env fparams fbody
continueEval env cont result
eval env cont (List (Atom "lambda" : varargs@(Atom _) : fbody)) = do
result <- makeVarargs varargs env [] fbody
continueEval env cont result
eval env cont (List [Atom "string-set!", Atom var, i, character]) = do
eval env (makeCPS env cont cpsStr) i
where
cpsStr :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsStr e c idx _ = eval e (makeCPSWArgs e c cpsSubStr $ [idx]) =<< getVar e var
cpsSubStr :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsSubStr e c str (Just [idx]) =
substr(str, character, idx) >>= setVar e var >>= continueEval e c
cpsSubStr _ _ _ _ = throwError $ InternalError "Invalid argument to cpsSubStr"
substr (String str, Char char, Number ii) = do
return $ String $ (take (fromInteger ii) . drop 0) str ++
[char] ++
(take (length str) . drop (fromInteger ii + 1)) str
substr (String _, Char _, n) = throwError $ TypeMismatch "number" n
substr (String _, c, _) = throwError $ TypeMismatch "character" c
substr (s, _, _) = throwError $ TypeMismatch "string" s
eval _ _ (List [Atom "string-set!" , nonvar , _ , _ ]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "string-set!" : args)) = throwError $ NumArgs 3 args
eval env cont (List [Atom "set-car!", Atom var, argObj]) = do
continueEval env (makeCPS env cont cpsObj) =<< getVar env var
where
cpsObj :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsObj _ _ obj@(List []) _ = throwError $ TypeMismatch "pair" obj
cpsObj e c obj@(List (_:_)) _ = eval e (makeCPSWArgs e c cpsSet $ [obj]) argObj
cpsObj e c obj@(DottedList _ _) _ = eval e (makeCPSWArgs e c cpsSet $ [obj]) argObj
cpsObj _ _ obj _ = throwError $ TypeMismatch "pair" obj
cpsSet :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsSet e c obj (Just [List (_ : ls)]) = setVar e var (List (obj : ls)) >>= continueEval e c
cpsSet e c obj (Just [DottedList (_ : ls) l]) = setVar e var (DottedList (obj : ls) l) >>= continueEval e c
cpsSet _ _ _ _ = throwError $ InternalError "Unexpected argument to cpsSet"
eval _ _ (List [Atom "set-car!" , nonvar , _ ]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "set-car!" : args)) = throwError $ NumArgs 2 args
eval env cont (List [Atom "set-cdr!", Atom var, argObj]) = do
continueEval env (makeCPS env cont cpsObj) =<< getVar env var
where
cpsObj :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsObj _ _ pair@(List []) _ = throwError $ TypeMismatch "pair" pair
cpsObj e c pair@(List (_:_)) _ = eval e (makeCPSWArgs e c cpsSet $ [pair]) argObj
cpsObj e c pair@(DottedList _ _) _ = eval e (makeCPSWArgs e c cpsSet $ [pair]) argObj
cpsObj _ _ pair _ = throwError $ TypeMismatch "pair" pair
cpsSet :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsSet e c obj (Just [List (l : _)]) = setVar e var (DottedList [l] obj) >>= continueEval e c
cpsSet e c obj (Just [DottedList (l : _) _]) = setVar e var (DottedList [l] obj) >>= continueEval e c
cpsSet _ _ _ _ = throwError $ InternalError "Unexpected argument to cpsSet"
eval _ _ (List [Atom "set-cdr!" , nonvar , _ ]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "set-cdr!" : args)) = throwError $ NumArgs 2 args
eval env cont (List [Atom "vector-set!", Atom var, i, object]) = do
eval env (makeCPS env cont cpsObj) i
where
cpsObj :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsObj e c idx _ = eval e (makeCPSWArgs e c cpsVec $ [idx]) object
cpsVec :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsVec e c obj (Just [idx]) = eval e (makeCPSWArgs e c cpsUpdateVec $ [idx, obj]) =<< getVar e var
cpsVec _ _ _ _ = throwError $ InternalError "Invalid argument to cpsVec"
cpsUpdateVec :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsUpdateVec e c vec (Just [idx, obj]) =
updateVector vec idx obj >>= setVar e var >>= continueEval e c
cpsUpdateVec _ _ _ _ = throwError $ InternalError "Invalid argument to cpsUpdateVec"
updateVector :: LispVal -> LispVal -> LispVal -> IOThrowsError LispVal
updateVector (Vector vec) (Number idx) obj = return $ Vector $ vec//[(fromInteger idx, obj)]
updateVector v _ _ = throwError $ TypeMismatch "vector" v
eval _ _ (List [Atom "vector-set!" , nonvar , _ , _]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "vector-set!" : args)) = throwError $ NumArgs 3 args
eval env cont (List [Atom "hash-table-set!", Atom var, rkey, rvalue]) = do
eval env (makeCPS env cont cpsValue) rkey
where
cpsValue :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsValue e c key _ = eval e (makeCPSWArgs e c cpsH $ [key]) rvalue
cpsH :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsH e c value (Just [key]) = eval e (makeCPSWArgs e c cpsEvalH $ [key, value]) =<< getVar e var
cpsH _ _ _ _ = throwError $ InternalError "Invalid argument to cpsH"
cpsEvalH :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsEvalH e c h (Just [key, value]) = do
case h of
HashTable ht -> do
setVar env var (HashTable $ Data.Map.insert key value ht) >>= eval e c
other -> throwError $ TypeMismatch "hash-table" other
cpsEvalH _ _ _ _ = throwError $ InternalError "Invalid argument to cpsEvalH"
eval _ _ (List [Atom "hash-table-set!" , nonvar , _ , _]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "hash-table-set!" : args)) = throwError $ NumArgs 3 args
eval env cont (List [Atom "hash-table-delete!", Atom var, rkey]) = do
eval env (makeCPS env cont cpsH) rkey
where
cpsH :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsH e c key _ = eval e (makeCPSWArgs e c cpsEvalH $ [key]) =<< getVar e var
cpsEvalH :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsEvalH e c h (Just [key]) = do
case h of
HashTable ht -> do
setVar env var (HashTable $ Data.Map.delete key ht) >>= eval e c
other -> throwError $ TypeMismatch "hash-table" other
cpsEvalH _ _ _ _ = throwError $ InternalError "Invalid argument to cpsEvalH"
eval _ _ (List [Atom "hash-table-delete!" , nonvar , _]) = throwError $ TypeMismatch "variable" nonvar
eval _ _ (List (Atom "hash-table-delete!" : args)) = throwError $ NumArgs 2 args
eval env cont (List (function : functionArgs)) = do
eval env (makeCPSWArgs env cont cpsPrepArgs $ functionArgs) function
where cpsPrepArgs :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsPrepArgs e c func (Just args) =
case (args) of
[] -> apply c func []
[a] -> eval env (makeCPSWArgs e c cpsEvalArgs $ [func, List [], List []]) a
(a:as) -> eval env (makeCPSWArgs e c cpsEvalArgs $ [func, List [], List as]) a
cpsPrepArgs _ _ _ Nothing = throwError $ Default "Unexpected error in function application (1)"
cpsEvalArgs :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsEvalArgs e c evaledArg (Just [func, List argsEvaled, List argsRemaining]) =
case argsRemaining of
[] -> apply c func (argsEvaled ++ [evaledArg])
[a] -> eval e (makeCPSWArgs e c cpsEvalArgs $ [func, List (argsEvaled ++ [evaledArg]), List []]) a
(a:as) -> eval e (makeCPSWArgs e c cpsEvalArgs $ [func, List (argsEvaled ++ [evaledArg]), List as]) a
cpsEvalArgs _ _ _ (Just _) = throwError $ Default "Unexpected error in function application (1)"
cpsEvalArgs _ _ _ Nothing = throwError $ Default "Unexpected error in function application (2)"
eval _ _ badForm = throwError $ BadSpecialForm "Unrecognized special form" badForm
makeFunc ::
(Monad m) =>
Maybe String -> Env -> [LispVal] -> [LispVal] -> m LispVal
makeFunc varargs env fparams fbody = return $ Func (map showVal fparams) varargs fbody env
makeNormalFunc :: (Monad m) => Env
-> [LispVal]
-> [LispVal]
-> m LispVal
makeNormalFunc = makeFunc Nothing
makeVarargs :: (Monad m) => LispVal -> Env
-> [LispVal]
-> [LispVal]
-> m LispVal
makeVarargs = makeFunc . Just . showVal
apply :: LispVal -> LispVal -> [LispVal] -> IOThrowsError LispVal
apply _ cont@(Continuation env ccont ncont _ ndynwind) args = do
case ndynwind of
Just ([DynamicWinders beforeFunc _]) -> apply (makeCPS env cont cpsApply) beforeFunc []
_ -> doApply env cont
where
cpsApply :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsApply e c _ _ = doApply e c
doApply e c =
case (toInteger $ length args) of
0 -> throwError $ NumArgs 1 []
1 -> continueEval e c $ head args
_ ->
continueEval e (Continuation env ccont ncont (Just $ tail args) ndynwind) $ head args
apply cont (IOFunc func) args = do
result <- func args
case cont of
Continuation cEnv _ _ _ _ -> continueEval cEnv cont result
_ -> return result
apply cont (EvalFunc func) args = do
func (cont : args)
apply cont (PrimitiveFunc func) args = do
result <- liftThrows $ func args
case cont of
Continuation cEnv _ _ _ _ -> continueEval cEnv cont result
_ -> return result
apply cont (Func aparams avarargs abody aclosure) args =
if num aparams /= num args && avarargs == Nothing
then throwError $ NumArgs (num aparams) args
else (liftIO $ extendEnv aclosure $ zip (map ((,) varNamespace) aparams) args) >>= bindVarArgs avarargs >>= (evalBody abody)
where remainingArgs = drop (length aparams) args
num = toInteger . length
evalBody evBody env = case cont of
Continuation _ (Just (SchemeBody cBody)) (Just cCont) _ cDynWind -> if length cBody == 0
then continueWCont env (evBody) cCont cDynWind
else continueWCont env (evBody) cont cDynWind
Continuation _ _ _ _ cDynWind -> continueWCont env (evBody) cont cDynWind
_ -> continueWCont env (evBody) cont Nothing
continueWCont cwcEnv cwcBody cwcCont cwcDynWind =
continueEval cwcEnv (Continuation cwcEnv (Just (SchemeBody cwcBody)) (Just cwcCont) Nothing cwcDynWind) $ Nil ""
bindVarArgs arg env = case arg of
Just argName -> liftIO $ extendEnv env [((varNamespace, argName), List $ remainingArgs)]
Nothing -> return env
apply _ func args = throwError $ BadSpecialForm "Unable to evaluate form" $ List (func : args)
primitiveBindings :: IO Env
primitiveBindings = nullEnv >>= (flip extendEnv $ map (domakeFunc IOFunc) ioPrimitives
++ map (domakeFunc EvalFunc) evalFunctions
++ map (domakeFunc PrimitiveFunc) primitives)
where domakeFunc constructor (var, func) = ((varNamespace, var), constructor func)
evalFunctions :: [(String, [LispVal] -> IOThrowsError LispVal)]
evalFunctions = [
("apply", evalfuncApply)
, ("call-with-current-continuation", evalfuncCallCC)
, ("call-with-values", evalfuncCallWValues)
, ("dynamic-wind", evalfuncDynamicWind)
, ("eval", evalfuncEval)
, ("load", evalfuncLoad)
]
evalfuncApply, evalfuncDynamicWind, evalfuncEval, evalfuncLoad, evalfuncCallCC, evalfuncCallWValues :: [LispVal] -> IOThrowsError LispVal
evalfuncDynamicWind [cont@(Continuation env _ _ _ _), beforeFunc, thunkFunc, afterFunc] = do
apply (makeCPS env cont cpsThunk) beforeFunc []
where
cpsThunk, cpsAfter :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsThunk e (Continuation ce cc cnc ca _ ) _ _ = apply (Continuation e (Just (HaskellBody cpsAfter Nothing))
(Just (Continuation ce cc cnc ca
Nothing))
Nothing
(Just ([DynamicWinders beforeFunc afterFunc])))
thunkFunc []
cpsThunk _ _ _ _ = throwError $ Default "Unexpected error in cpsThunk during (dynamic-wind)"
cpsAfter _ c _ _ = apply c afterFunc []
evalfuncDynamicWind (_ : args) = throwError $ NumArgs 3 args
evalfuncDynamicWind _ = throwError $ NumArgs 3 []
evalfuncCallWValues [cont@(Continuation env _ _ _ _), producer, consumer] = do
apply (makeCPS env cont cpsEval) producer []
where
cpsEval :: Env -> LispVal -> LispVal -> Maybe [LispVal] -> IOThrowsError LispVal
cpsEval _ c@(Continuation _ _ _ (Just xargs) _) value _ = apply c consumer (value : xargs)
cpsEval _ c value _ = apply c consumer [value]
evalfuncCallWValues (_ : args) = throwError $ NumArgs 2 args
evalfuncCallWValues _ = throwError $ NumArgs 2 []
evalfuncApply [cont@(Continuation _ _ _ _ _), func, List args] = apply cont func args
evalfuncApply (_ : args) = throwError $ NumArgs 2 args
evalfuncApply _ = throwError $ NumArgs 2 []
evalfuncLoad [cont@(Continuation env _ _ _ _), String filename] = do
result <- load filename >>= liftM last . mapM (evaluate env (makeNullContinuation env))
continueEval env cont result
where evaluate env2 cont2 val2 = macroEval env2 val2 >>= eval env2 cont2
evalfuncLoad (_ : args) = throwError $ NumArgs 1 args
evalfuncLoad _ = throwError $ NumArgs 1 []
evalfuncEval [cont@(Continuation env _ _ _ _), val] = eval env cont val
evalfuncEval (_ : args) = throwError $ NumArgs 1 args
evalfuncEval _ = throwError $ NumArgs 1 []
evalfuncCallCC [cont@(Continuation _ _ _ _ _), func] = do
case func of
PrimitiveFunc f -> do
result <- liftThrows $ f [cont]
case cont of
Continuation cEnv _ _ _ _ -> continueEval cEnv cont result
_ -> return result
Func aparams _ _ _ ->
if (toInteger $ length aparams) == 1
then apply cont func [cont]
else throwError $ NumArgs (toInteger $ length aparams) [cont]
other -> throwError $ TypeMismatch "procedure" other
evalfuncCallCC (_ : args) = throwError $ NumArgs 1 args
evalfuncCallCC _ = throwError $ NumArgs 1 []
ioPrimitives :: [(String, [LispVal] -> IOThrowsError LispVal)]
ioPrimitives = [("open-input-file", makePort ReadMode),
("open-output-file", makePort WriteMode),
("close-input-port", closePort),
("close-output-port", closePort),
("input-port?", isInputPort),
("output-port?", isOutputPort),
("current-input-port", currentInputPort),
("current-output-port", currentOutputPort),
("read", readProc),
("read-char", readCharProc hGetChar),
("peek-char", readCharProc hLookAhead),
("write", writeProc (\port obj -> hPrint port obj)),
("write-char", writeCharProc),
("display", writeProc (\port obj -> case obj of
String str -> hPutStr port str
_ -> hPutStr port $ show obj)),
("read-contents", readContents),
("read-all", readAll)]
makePort :: IOMode -> [LispVal] -> IOThrowsError LispVal
makePort mode [String filename] = liftM Port $ liftIO $ openFile filename mode
makePort _ [] = throwError $ NumArgs 1 []
makePort _ args@(_ : _) = throwError $ NumArgs 1 args
closePort :: [LispVal] -> IOThrowsError LispVal
closePort [Port port] = liftIO $ hClose port >> (return $ Bool True)
closePort _ = return $ Bool False
currentInputPort, currentOutputPort :: [LispVal] -> IOThrowsError LispVal
currentInputPort _ = return $ Port stdin
currentOutputPort _ = return $ Port stdout
isInputPort, isOutputPort :: [LispVal] -> IOThrowsError LispVal
isInputPort [Port port] = liftM Bool $ liftIO $ hIsReadable port
isInputPort _ = return $ Bool False
isOutputPort [Port port] = liftM Bool $ liftIO $ hIsWritable port
isOutputPort _ = return $ Bool False
readProc :: [LispVal] -> IOThrowsError LispVal
readProc [] = readProc [Port stdin]
readProc [Port port] = do
input <- liftIO $ try (liftIO $ hGetLine port)
case input of
Left e -> if isEOFError e
then return $ EOF
else throwError $ Default "I/O error reading from port"
Right inpStr -> do
liftThrows $ readExpr inpStr
readProc args@(_ : _) = throwError $ BadSpecialForm "" $ List args
readCharProc :: (Handle -> IO Char) -> [LispVal] -> IOThrowsError LispVal
readCharProc func [] = readCharProc func [Port stdin]
readCharProc func [Port port] = do
liftIO $ hSetBuffering port NoBuffering
input <- liftIO $ try (liftIO $ func port)
liftIO $ hSetBuffering port LineBuffering
case input of
Left e -> if isEOFError e
then return $ EOF
else throwError $ Default "I/O error reading from port"
Right inpChr -> do
return $ Char inpChr
readCharProc _ args@(_ : _) = throwError $ BadSpecialForm "" $ List args
writeProc func [obj] = writeProc func [obj, Port stdout]
writeProc func [obj, Port port] = do
output <- liftIO $ try (liftIO $ func port obj)
case output of
Left _ -> throwError $ Default "I/O error writing to port"
Right _ -> return $ Nil ""
writeProc _ other = if length other == 2
then throwError $ TypeMismatch "(value port)" $ List other
else throwError $ NumArgs 2 other
writeCharProc :: [LispVal] -> IOThrowsError LispVal
writeCharProc [obj] = writeCharProc [obj, Port stdout]
writeCharProc [obj@(Char _), Port port] = do
output <- liftIO $ try (liftIO $ (hPutStr port $ show obj))
case output of
Left _ -> throwError $ Default "I/O error writing to port"
Right _ -> return $ Nil ""
writeCharProc other = if length other == 2
then throwError $ TypeMismatch "(character port)" $ List other
else throwError $ NumArgs 2 other
readContents :: [LispVal] -> IOThrowsError LispVal
readContents [String filename] = liftM String $ liftIO $ readFile filename
readContents [] = throwError $ NumArgs 1 []
readContents args@(_ : _) = throwError $ NumArgs 1 args
load :: String -> IOThrowsError [LispVal]
load filename = do
result <- liftIO $ doesFileExist filename
if result
then (liftIO $ readFile filename) >>= liftThrows . readExprList
else throwError $ Default $ "File does not exist: " ++ filename
readAll :: [LispVal] -> IOThrowsError LispVal
readAll [String filename] = liftM List $ load filename
readAll [] = throwError $ NumArgs 1 []
readAll args@(_ : _) = throwError $ NumArgs 1 args
primitives :: [(String, [LispVal] -> ThrowsError LispVal)]
primitives = [("+", numAdd),
("-", numSub),
("*", numMul),
("/", numDiv),
("modulo", numericBinop mod),
("quotient", numericBinop quot),
("remainder", numericBinop rem),
("round", numRound),
("floor", numFloor),
("ceiling", numCeiling),
("truncate", numTruncate),
("numerator", numNumerator),
("denominator", numDenominator),
("exp", numExp),
("log", numLog),
("sin", numSin),
("cos", numCos),
("tan", numTan),
("asin", numAsin),
("acos", numAcos),
("atan", numAtan),
("sqrt", numSqrt),
("expt", numExpt),
("make-rectangular", numMakeRectangular),
("make-polar", numMakePolar),
("real-part", numRealPart ),
("imag-part", numImagPart),
("magnitude", numMagnitude),
("angle", numAngle ),
("exact->inexact", numExact2Inexact),
("inexact->exact", numInexact2Exact),
("number->string", num2String),
("=", numBoolBinopEq),
(">", numBoolBinopGt),
(">=", numBoolBinopGte),
("<", numBoolBinopLt),
("<=", numBoolBinopLte),
("&&", boolBoolBinop (&&)),
("||", boolBoolBinop (||)),
("string=?", strBoolBinop (==)),
("string<?", strBoolBinop (<)),
("string>?", strBoolBinop (>)),
("string<=?", strBoolBinop (<=)),
("string>=?", strBoolBinop (>=)),
("string-ci=?", stringCIEquals),
("string-ci<?", stringCIBoolBinop (<)),
("string-ci>?", stringCIBoolBinop (>)),
("string-ci<=?", stringCIBoolBinop (<=)),
("string-ci>=?", stringCIBoolBinop (>=)),
("car", car),
("cdr", cdr),
("cons", cons),
("eq?", eqv),
("eqv?", eqv),
("equal?", equal),
("pair?", isDottedList),
("procedure?", isProcedure),
("number?", isNumber),
("complex?", isComplex),
("real?", isReal),
("rational?", isRational),
("integer?", isInteger),
("list?", unaryOp isList),
("null?", isNull),
("eof-object?", isEOFObject),
("symbol?", isSymbol),
("symbol->string", symbol2String),
("string->symbol", string2Symbol),
("char?", isChar),
("vector?", unaryOp isVector),
("make-vector", makeVector),
("vector", buildVector),
("vector-length", vectorLength),
("vector-ref", vectorRef),
("vector->list", vectorToList),
("list->vector", listToVector),
("make-hash-table", hashTblMake),
("hash-table?", isHashTbl),
("hash-table-exists?", hashTblExists),
("hash-table-ref", hashTblRef),
("hash-table-size", hashTblSize),
("hash-table->alist", hashTbl2List),
("hash-table-keys", hashTblKeys),
("hash-table-values", hashTblValues),
("hash-table-copy", hashTblCopy),
("string?", isString),
("string", buildString),
("make-string", makeString),
("string-length", stringLength),
("string-ref", stringRef),
("substring", substring),
("string-append", stringAppend),
("string->number", stringToNumber),
("string->list", stringToList),
("list->string", listToString),
("string-copy", stringCopy),
("boolean?", isBoolean)]
data Unpacker = forall a. Eq a => AnyUnpacker (LispVal -> ThrowsError a)
unpackEquals :: LispVal -> LispVal -> Unpacker -> ThrowsError Bool
unpackEquals arg1 arg2 (AnyUnpacker unpacker) =
do unpacked1 <- unpacker arg1
unpacked2 <- unpacker arg2
return $ unpacked1 == unpacked2
`catchError` (const $ return False)
boolBinop :: (LispVal -> ThrowsError a) -> (a -> a -> Bool) -> [LispVal] -> ThrowsError LispVal
boolBinop unpacker op args = if length args /= 2
then throwError $ NumArgs 2 args
else do left <- unpacker $ args !! 0
right <- unpacker $ args !! 1
return $ Bool $ left `op` right
unaryOp :: (LispVal -> ThrowsError LispVal) -> [LispVal] -> ThrowsError LispVal
unaryOp f [v] = f v
unaryOp _ [] = throwError $ NumArgs 1 []
unaryOp _ args@(_ : _) = throwError $ NumArgs 1 args
strBoolBinop :: (String -> String -> Bool) -> [LispVal] -> ThrowsError LispVal
strBoolBinop = boolBinop unpackStr
boolBoolBinop :: (Bool -> Bool -> Bool) -> [LispVal] -> ThrowsError LispVal
boolBoolBinop = boolBinop unpackBool
unpackStr :: LispVal -> ThrowsError String
unpackStr (String s) = return s
unpackStr (Number s) = return $ show s
unpackStr (Bool s) = return $ show s
unpackStr notString = throwError $ TypeMismatch "string" notString
unpackBool :: LispVal -> ThrowsError Bool
unpackBool (Bool b) = return b
unpackBool notBool = throwError $ TypeMismatch "boolean" notBool
car :: [LispVal] -> ThrowsError LispVal
car [List (x : _)] = return x
car [DottedList (x : _) _] = return x
car [badArg] = throwError $ TypeMismatch "pair" badArg
car badArgList = throwError $ NumArgs 1 badArgList
cdr :: [LispVal] -> ThrowsError LispVal
cdr [List (_ : xs)] = return $ List xs
cdr [DottedList [_] x] = return x
cdr [DottedList (_ : xs) x] = return $ DottedList xs x
cdr [badArg] = throwError $ TypeMismatch "pair" badArg
cdr badArgList = throwError $ NumArgs 1 badArgList
cons :: [LispVal] -> ThrowsError LispVal
cons [x1, List []] = return $ List [x1]
cons [x, List xs] = return $ List $ x : xs
cons [x, DottedList xs xlast] = return $ DottedList (x : xs) xlast
cons [x1, x2] = return $ DottedList [x1] x2
cons badArgList = throwError $ NumArgs 2 badArgList
equal :: [LispVal] -> ThrowsError LispVal
equal [(Vector arg1), (Vector arg2)] = eqvList equal [List $ (elems arg1), List $ (elems arg2)]
equal [l1@(List _), l2@(List _)] = eqvList equal [l1, l2]
equal [(DottedList xs x), (DottedList ys y)] = equal [List $ xs ++ [x], List $ ys ++ [y]]
equal [arg1, arg2] = do
primitiveEquals <- liftM or $ mapM (unpackEquals arg1 arg2)
[AnyUnpacker unpackNum, AnyUnpacker unpackStr, AnyUnpacker unpackBool]
eqvEquals <- eqv [arg1, arg2]
return $ Bool $ (primitiveEquals || let (Bool x) = eqvEquals in x)
equal badArgList = throwError $ NumArgs 2 badArgList
makeVector, buildVector, vectorLength, vectorRef, vectorToList, listToVector :: [LispVal] -> ThrowsError LispVal
makeVector [(Number n)] = makeVector [Number n, List []]
makeVector [(Number n), a] = do
let l = replicate (fromInteger n) a
return $ Vector $ (listArray (0, length l 1)) l
makeVector [badType] = throwError $ TypeMismatch "integer" badType
makeVector badArgList = throwError $ NumArgs 1 badArgList
buildVector (o:os) = do
let lst = o:os
return $ Vector $ (listArray (0, length lst 1)) lst
buildVector badArgList = throwError $ NumArgs 1 badArgList
vectorLength [(Vector v)] = return $ Number $ toInteger $ length (elems v)
vectorLength [badType] = throwError $ TypeMismatch "vector" badType
vectorLength badArgList = throwError $ NumArgs 1 badArgList
vectorRef [(Vector v), (Number n)] = return $ v ! (fromInteger n)
vectorRef [badType] = throwError $ TypeMismatch "vector integer" badType
vectorRef badArgList = throwError $ NumArgs 2 badArgList
vectorToList [(Vector v)] = return $ List $ elems v
vectorToList [badType] = throwError $ TypeMismatch "vector" badType
vectorToList badArgList = throwError $ NumArgs 1 badArgList
listToVector [(List l)] = return $ Vector $ (listArray (0, length l 1)) l
listToVector [badType] = throwError $ TypeMismatch "list" badType
listToVector badArgList = throwError $ NumArgs 1 badArgList
hashTblMake, isHashTbl, hashTblExists, hashTblRef, hashTblSize, hashTbl2List, hashTblKeys, hashTblValues, hashTblCopy:: [LispVal] -> ThrowsError LispVal
hashTblMake _ = return $ HashTable $ Data.Map.fromList []
isHashTbl [(HashTable _)] = return $ Bool True
isHashTbl _ = return $ Bool False
hashTblExists [(HashTable ht), key@(_)] = do
case Data.Map.lookup key ht of
Just _ -> return $ Bool True
Nothing -> return $ Bool False
hashTblExists [] = throwError $ NumArgs 2 []
hashTblExists args@(_ : _) = throwError $ NumArgs 2 args
hashTblRef [(HashTable ht), key@(_)] = do
case Data.Map.lookup key ht of
Just val -> return $ val
Nothing -> throwError $ BadSpecialForm "Hash table does not contain key" key
hashTblRef [(HashTable ht), key@(_), Func _ _ _ _] = do
case Data.Map.lookup key ht of
Just val -> return $ val
Nothing -> throwError $ NotImplemented "thunk"
hashTblRef [badType] = throwError $ TypeMismatch "hash-table" badType
hashTblRef badArgList = throwError $ NumArgs 2 badArgList
hashTblSize [(HashTable ht)] = return $ Number $ toInteger $ Data.Map.size ht
hashTblSize [badType] = throwError $ TypeMismatch "hash-table" badType
hashTblSize badArgList = throwError $ NumArgs 1 badArgList
hashTbl2List [(HashTable ht)] = do
return $ List $ map (\(k, v) -> List [k, v]) $ Data.Map.toList ht
hashTbl2List [badType] = throwError $ TypeMismatch "hash-table" badType
hashTbl2List badArgList = throwError $ NumArgs 1 badArgList
hashTblKeys [(HashTable ht)] = do
return $ List $ map (\(k, _) -> k) $ Data.Map.toList ht
hashTblKeys [badType] = throwError $ TypeMismatch "hash-table" badType
hashTblKeys badArgList = throwError $ NumArgs 1 badArgList
hashTblValues [(HashTable ht)] = do
return $ List $ map (\(_, v) -> v) $ Data.Map.toList ht
hashTblValues [badType] = throwError $ TypeMismatch "hash-table" badType
hashTblValues badArgList = throwError $ NumArgs 1 badArgList
hashTblCopy [(HashTable ht)] = do
return $ HashTable $ Data.Map.fromList $ Data.Map.toList ht
hashTblCopy [badType] = throwError $ TypeMismatch "hash-table" badType
hashTblCopy badArgList = throwError $ NumArgs 1 badArgList
buildString :: [LispVal] -> ThrowsError LispVal
buildString [(Char c)] = return $ String [c]
buildString (Char c:rest) = do
cs <- buildString rest
case cs of
String s -> return $ String $ [c] ++ s
badType -> throwError $ TypeMismatch "character" badType
buildString [badType] = throwError $ TypeMismatch "character" badType
buildString badArgList = throwError $ NumArgs 1 badArgList
makeString :: [LispVal] -> ThrowsError LispVal
makeString [(Number n)] = return $ doMakeString n ' ' ""
makeString [(Number n), (Char c)] = return $ doMakeString n c ""
makeString badArgList = throwError $ NumArgs 1 badArgList
doMakeString :: forall a.(Num a) => a -> Char -> String -> LispVal
doMakeString n char s =
if n == 0
then String s
else doMakeString (n 1) char (s ++ [char])
stringLength :: [LispVal] -> ThrowsError LispVal
stringLength [String s] = return $ Number $ foldr (const (+1)) 0 s
stringLength [badType] = throwError $ TypeMismatch "string" badType
stringLength badArgList = throwError $ NumArgs 1 badArgList
stringRef :: [LispVal] -> ThrowsError LispVal
stringRef [(String s), (Number k)] = return $ Char $ s !! fromInteger k
stringRef [badType] = throwError $ TypeMismatch "string number" badType
stringRef badArgList = throwError $ NumArgs 2 badArgList
substring :: [LispVal] -> ThrowsError LispVal
substring [(String s), (Number start), (Number end)] =
do let slength = fromInteger $ end start
let begin = fromInteger start
return $ String $ (take slength . drop begin) s
substring [badType] = throwError $ TypeMismatch "string number number" badType
substring badArgList = throwError $ NumArgs 3 badArgList
stringCIEquals :: [LispVal] -> ThrowsError LispVal
stringCIEquals [(String str1), (String str2)] = do
if (length str1) /= (length str2)
then return $ Bool False
else return $ Bool $ ciCmp str1 str2 0
where ciCmp s1 s2 idx = if idx == (length s1)
then True
else if (toLower $ s1 !! idx) == (toLower $ s2 !! idx)
then ciCmp s1 s2 (idx + 1)
else False
stringCIEquals [badType] = throwError $ TypeMismatch "string string" badType
stringCIEquals badArgList = throwError $ NumArgs 2 badArgList
stringCIBoolBinop :: ([Char] -> [Char] -> Bool) -> [LispVal] -> ThrowsError LispVal
stringCIBoolBinop op [(String s1), (String s2)] = boolBinop unpackStr op [(String $ strToLower s1), (String $ strToLower s2)]
where strToLower str = map (toLower) str
stringCIBoolBinop _ [badType] = throwError $ TypeMismatch "string string" badType
stringCIBoolBinop _ badArgList = throwError $ NumArgs 2 badArgList
stringAppend :: [LispVal] -> ThrowsError LispVal
stringAppend [(String s)] = return $ String s
stringAppend (String st:sts) = do
rest <- stringAppend sts
case rest of
String s -> return $ String $ st ++ s
other -> throwError $ TypeMismatch "string" other
stringAppend [badType] = throwError $ TypeMismatch "string" badType
stringAppend badArgList = throwError $ NumArgs 1 badArgList
stringToNumber :: [LispVal] -> ThrowsError LispVal
stringToNumber [(String s)] = do
result <- (readExpr s)
case result of
n@(Number _) -> return n
n@(Rational _) -> return n
n@(Float _) -> return n
n@(Complex _) -> return n
_ -> return $ Bool False
stringToNumber [(String s), Number radix] = do
case radix of
2 -> stringToNumber [String $ "#b" ++ s]
8 -> stringToNumber [String $ "#o" ++ s]
10 -> stringToNumber [String s]
16 -> stringToNumber [String $ "#x" ++ s]
_ -> throwError $ Default $ "Invalid radix: " ++ show radix
stringToNumber [badType] = throwError $ TypeMismatch "string" badType
stringToNumber badArgList = throwError $ NumArgs 1 badArgList
stringToList :: [LispVal] -> ThrowsError LispVal
stringToList [(String s)] = return $ List $ map (Char) s
stringToList [badType] = throwError $ TypeMismatch "string" badType
stringToList badArgList = throwError $ NumArgs 1 badArgList
listToString :: [LispVal] -> ThrowsError LispVal
listToString [(List [])] = return $ String ""
listToString [(List l)] = buildString l
listToString [badType] = throwError $ TypeMismatch "list" badType
listToString [] = throwError $ NumArgs 1 []
listToString args@(_ : _) = throwError $ NumArgs 1 args
stringCopy :: [LispVal] -> ThrowsError LispVal
stringCopy [String s] = return $ String s
stringCopy [badType] = throwError $ TypeMismatch "string" badType
stringCopy badArgList = throwError $ NumArgs 2 badArgList
isDottedList :: [LispVal] -> ThrowsError LispVal
isDottedList ([DottedList _ _]) = return $ Bool True
isDottedList ([List []]) = return $ Bool False
isDottedList ([List _]) = return $ Bool True
isDottedList _ = return $ Bool False
isProcedure :: [LispVal] -> ThrowsError LispVal
isProcedure ([Continuation _ _ _ _ _]) = return $ Bool True
isProcedure ([PrimitiveFunc _]) = return $ Bool True
isProcedure ([Func _ _ _ _]) = return $ Bool True
isProcedure ([IOFunc _]) = return $ Bool True
isProcedure ([EvalFunc _]) = return $ Bool True
isProcedure _ = return $ Bool False
isVector, isList :: LispVal -> ThrowsError LispVal
isVector (Vector _) = return $ Bool True
isVector _ = return $ Bool False
isList (List _) = return $ Bool True
isList _ = return $ Bool False
isNull :: [LispVal] -> ThrowsError LispVal
isNull ([List []]) = return $ Bool True
isNull _ = return $ Bool False
isEOFObject :: [LispVal] -> ThrowsError LispVal
isEOFObject ([EOF]) = return $ Bool True
isEOFObject _ = return $ Bool False
isSymbol :: [LispVal] -> ThrowsError LispVal
isSymbol ([Atom _]) = return $ Bool True
isSymbol _ = return $ Bool False
symbol2String :: [LispVal] -> ThrowsError LispVal
symbol2String ([Atom a]) = return $ String a
symbol2String [notAtom] = throwError $ TypeMismatch "symbol" notAtom
symbol2String [] = throwError $ NumArgs 1 []
symbol2String args@(_ : _) = throwError $ NumArgs 1 args
string2Symbol :: [LispVal] -> ThrowsError LispVal
string2Symbol ([String s]) = return $ Atom s
string2Symbol [] = throwError $ NumArgs 1 []
string2Symbol [notString] = throwError $ TypeMismatch "string" notString
string2Symbol args@(_ : _) = throwError $ NumArgs 1 args
isChar :: [LispVal] -> ThrowsError LispVal
isChar ([Char _]) = return $ Bool True
isChar _ = return $ Bool False
isString :: [LispVal] -> ThrowsError LispVal
isString ([String _]) = return $ Bool True
isString _ = return $ Bool False
isBoolean :: [LispVal] -> ThrowsError LispVal
isBoolean ([Bool _]) = return $ Bool True
isBoolean _ = return $ Bool False