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module Interpreter where
import Control.Monad.Except
import Data.Char
import Data.Map (Map, (!))
import qualified Data.Map as M
import LTypes
import Utils
-- | Wait for unbuffered input (any key) from stdin. If 'q', return 'ExecExit', otherwise 'ExecContinue'.
-- If not in debug mode, immediately return 'ExecContinue' without waiting.
debugWaitForChar Config {configDebugMode = mode} = do
if mode
then do
c <- getChar
pure $ case c of
'q' -> ExecExit
_ -> ExecContinue
else pure ExecContinue
-- | If in debug mode, print the supplied message, automatically prefixed with "[debug]". Otherwise, no op.
debugPrint Config {configDebugMode = mode} message =
if mode
then liftIO $ putStrLn $ fmt "[debug] %%" [message]
else pure ()
-- |
interpretSource :: Config -> LState -> ExceptT LException IO LState
interpretSource config state@LState {lSource = []} = pure state
interpretSource config state@LState {lSource = (word : rest)} = do
liftIO $ debugPrint config $ fmt "processing %%, current state =" [show word]
liftIO $ debugState config state
newState <- interpretWord state {lSource = rest} word
step <- liftIO $ debugWaitForChar config
case step of
ExecContinue -> interpretSource config newState
ExecExit -> pure newState
interpretWord :: LState -> LWord -> ExceptT LException IO LState
-- non-nestable structures
interpretWord state@LState {lStack = stack, lPhraseDepth = phraseDepth} word@(LSymbol "define") =
pure $
state
{ lPhraseDepth = phraseDepth + 1,
lStack = word : stack
}
interpretWord state@LState {lDefs = defs, lStack = stack, lPhraseDepth = phraseDepth} word@(LSymbol ";") = do
let defineSpan = takeWhile (\word -> word /= LSymbol "define") stack
let newStack = dropWhile (\word -> word /= LSymbol "define") stack $> tail
(LSymbol identifier, body) <- consume1 LSymbolT (reverse defineSpan)
let newDefs = M.insert identifier body defs
pure $
state
{ lPhraseDepth = phraseDepth - 1,
lDefs = newDefs,
lStack = newStack
}
-- words that simply move from source to stack
interpretWord state@LState {lStack = stack} word@(LInteger _) = pure $ state {lStack = word : stack}
interpretWord state@LState {lStack = stack} word@(LFloat _) = pure $ state {lStack = word : stack}
interpretWord state@LState {lStack = stack} word@(LBool _) = pure $ state {lStack = word : stack}
interpretWord state@LState {lStack = stack} word@(LChar _) = pure $ state {lStack = word : stack}
interpretWord state@LState {lStack = stack} word@(LLabel _) = pure $ state {lStack = word : stack}
interpretWord state@LState {lStack = stack} word@(LPhrase _) = pure $ state {lStack = word : stack}
-- string literals
interpretWord state@LState {lSource = source, lStrLitRefMap = strLitRefMap} (LStringLitRef ref) =
let strLitP = strLitRefMap ! ref
in pure $ state {lSource = strLitP ++ source}
-- phrase markers are always evaled
interpretWord state@LState {lStack = stack, lPhraseDepth = phraseDepth} word@(LSymbol "[") =
pure $ state {lPhraseDepth = phraseDepth + 1, lStack = word : stack}
interpretWord state@LState {lStack = stack, lPhraseDepth = phraseDepth} word@(LSymbol "]") = do
(phrase, _ : stack') <- safeBreak (== LSymbol "[") (LException "phrase-start marker '[' missing in stack") stack
let newStack = LPhrase (reverse phrase) : stack'
pure $ state {lPhraseDepth = phraseDepth - 1, lStack = newStack}
-- definition lookup
interpretWord state@LState {lDefs = defs, lDict = dict, lSource = source, lPhraseDepth = phraseDepth, lStack = stack} word@(LSymbol symbol)
| phraseDepth == 0 =
case M.lookup symbol defs of
Just body -> pure $ state {lSource = body ++ source}
Nothing ->
case symbol of
"dup" -> pure $ state {lStack = head stack : stack}
"drop" -> pure $ state {lStack = tail stack}
"clear" -> pure $ state {lStack = []}
"noop" -> pure state
"true" -> pure $ state {lStack = LBool True : stack}
"false" -> pure $ state {lStack = LBool False : stack}
"not" -> do
(LBool a, stack') <- consume1 LBoolT stack
pure $ state {lStack = LBool (not a) : stack'}
"float" -> do
(LInteger a, stack') <- consume1 LIntegerT stack
pure $ state {lStack = LFloat (fromIntegral a) : stack'}
"round" -> do
(LFloat a, stack') <- consume1 LFloatT stack
pure $ state {lStack = LInteger (round a) : stack'}
"!" -> do
(LLabel a, b, stack') <- consume2 LLabelT AnyT stack
let newDict = M.insert a b dict
pure $ state {lDict = newDict, lStack = stack'}
"@" -> do
(LLabel a, stack') <- consume1 LLabelT stack
let lookupWord = dict ! a
pure $ state {lStack = lookupWord : stack'}
"forget" -> do
(LLabel a, stack') <- consume1 LLabelT stack
let newDict = M.delete a dict
pure $ state {lStack = stack', lDict = newDict}
"." -> do
(a, stack') <- consume1 AnyT stack
liftIO . putStrLn $ reprWord a
pure $ state {lStack = stack'}
"s." -> do
(wordP, stack') <- consume1 LPhraseT stack
let LPhrase ws = wordP
let isLChar w = case w of LChar _ -> True; _ -> False
unless (all isLChar ws) $ throwError $ LException $ fmt "cannot string-print heterogenous or non-string phrase: %%" [reprWord wordP]
let stringRepr = ws $> map (\(LChar c) -> c)
liftIO . putStrLn $ stringRepr
pure $ state {lStack = stack'}
"?" -> do
(LLabel a, stack') <- consume1 LLabelT stack
let lookupWord = dict ! a
liftIO . putStrLn $ reprWord lookupWord
pure $ state {lStack = stack'}
"+" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lAddNumbers b a
pure $ state {lStack = result : stack'}
"-" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lSubNumbers b a
pure $ state {lStack = result : stack'}
"*" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lMultiplyNumbers b a
pure $ state {lStack = result : stack'}
"/" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lDivideNumbers b a
pure $ state {lStack = result : stack'}
"mod" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lModNumbers b a
pure $ state {lStack = result : stack'}
"eq?" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
pure $ state {lStack = LBool (a == b) : stack'}
"gt?" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lGreaterThan b a
pure $ state {lStack = result : stack'}
"lt?" -> do
(a, b, stack') <- consume2 AnyT AnyT stack
result <- lLesserThan b a
pure $ state {lStack = result : stack'}
"unphrase" -> do
(LPhrase phrase, stack') <- consume1 LPhraseT stack
pure $ state {lSource = phrase ++ source, lStack = stack'}
"phrase" -> do
(LSymbol "]", stack') <- consume1 LSymbolT stack
(body, _ : newStack) <- safeBreak (== LSymbol "[") (LException "phrase-start marker '[' missing in stack") stack'
pure $ state {lStack = LPhrase (reverse body) : newStack}
"repr" -> do
(word, stack') <- consume1 AnyT stack
let reprStr = reprWord word $> map LChar .> LPhrase
pure $ state {lStack = reprStr : stack'}
"pop" -> do
(LPhrase phrase, stack') <- consume1 LPhraseT stack
let (first : rest) = phrase
pure $ state {lStack = first : LPhrase rest : stack'}
"stack-size" ->
let size = LInteger $ fromIntegral (length stack)
in pure $ state {lStack = size : stack}
"']" ->
pure $ state {lStack = LSymbol "]" : stack}
"'[" ->
pure $ state {lStack = LSymbol "[" : stack}
"cond" -> do
(fb, tb, LBool cond, stack') <- consume3 LPhraseT LPhraseT LBoolT stack
let LPhrase branch = if cond then tb else fb
let newSource = branch ++ source
pure $ state {lStack = stack', lSource = newSource}
"loop" -> do
(bodyP, condP, stack') <- consume2 LPhraseT LPhraseT stack
let (LPhrase body, LPhrase cond) = (bodyP, condP)
let ifWords =
concat
[ cond,
[LPhrase (body ++ [condP, bodyP, LSymbol "loop"])],
[LPhrase [], LSymbol "cond"]
]
let newSource = ifWords ++ source
pure $ state {lStack = stack', lSource = newSource}
_ -> throwError $ LException $ fmt "not defined: %%" [symbol]
| otherwise = pure $ state {lStack = word : stack}
lAddNumbers :: LWord -> LWord -> ExceptT LException IO LWord
lAddNumbers (LInteger a) (LInteger b) = pure $ LInteger (a + b)
lAddNumbers (LFloat a) (LFloat b) = pure $ LFloat (a + b)
lAddNumbers a b = throwError $ LException $ fmt "sum is not defined for %%, %%" [show a, show b]
lSubNumbers :: LWord -> LWord -> ExceptT LException IO LWord
lSubNumbers (LInteger a) (LInteger b) = pure $ LInteger (a - b)
lSubNumbers (LFloat a) (LFloat b) = pure $ LFloat (a - b)
lSubNumbers a b = throwError $ LException $ fmt "difference is not defined for %%, %%" [show a, show b]
lMultiplyNumbers :: LWord -> LWord -> ExceptT LException IO LWord
lMultiplyNumbers (LInteger a) (LInteger b) = pure $ LInteger (a * b)
lMultiplyNumbers (LFloat a) (LFloat b) = pure $ LFloat (a * b)
lMultiplyNumbers a b = throwError $ LException $ fmt "product is not defined for %%, %%" [show a, show b]
lDivideNumbers :: LWord -> LWord -> ExceptT LException IO LWord
lDivideNumbers (LInteger a) (LInteger b) =
case b of
0 -> throwError $ LException "division by zero"
_ -> pure $ LInteger (a `div` b)
lDivideNumbers (LFloat a) (LFloat b) =
case b of
0 -> throwError $ LException "division by zero"
_ -> pure $ LFloat (a / b)
lDivideNumbers a b = throwError $ LException $ fmt "division is not defined for %%, %%" [show a, show b]
lGreaterThan :: LWord -> LWord -> ExceptT LException IO LWord
lGreaterThan (LInteger a) (LInteger b) = pure $ LBool (a > b)
lGreaterThan (LFloat a) (LFloat b) = pure $ LBool (a > b)
lGreaterThan a b = throwError $ LException $ fmt "greater-than is not defined for %%, %%" [show a, show b]
lLesserThan :: LWord -> LWord -> ExceptT LException IO LWord
lLesserThan (LInteger a) (LInteger b) = pure $ LBool (a < b)
lLesserThan (LFloat a) (LFloat b) = pure $ LBool (a < b)
lLesserThan a b = throwError $ LException $ fmt "lesser-than is not defined for %%, %%" [show a, show b]
lModNumbers :: LWord -> LWord -> ExceptT LException IO LWord
lModNumbers (LInteger a) (LInteger b) = pure $ LInteger (a `mod` b)
lModNumbers a b = throwError $ LException $ fmt "modulo is not defined for %%, %%" [show a, show b]
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