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module Main where
import Data.Char
import System.Environment (getArgs)
import Utils
getFilename [] = error "empty argument list"
getFilename (f : fs) = f
data LWord
= LSymbol String
| LInteger Integer
deriving (Show)
reprWord (LSymbol a) = a
reprWord (LInteger a) = show a
parseWord rawStr
| all isDigit rawStr = LInteger (read rawStr)
| otherwise = LSymbol rawStr
parseSource source = source $> words .> map parseWord
interpretSource :: [LWord] -> [LWord] -> IO ()
interpretSource _ [] = putStrLn "done"
interpretSource stack (word : rest) = do
newStack <- interpretWord stack word
interpretSource newStack rest
interpretWord :: [LWord] -> LWord -> IO [LWord]
interpretWord stack word@(LInteger value) = pure $ word : stack
interpretWord (a : stack) word@(LSymbol ".") = do
putStrLn $ reprWord a
pure stack
interpretWord ((LInteger a) : (LInteger b) : stack) word@(LSymbol "+") = pure $ LInteger (a + b) : stack
interpretWord _ other = error $ "[error] runtime error at " ++ show other
main :: IO ()
main = do
args <- getArgs
let filename = getFilename args
putStrLn $ "[info] executing file " ++ filename
source <- readFile filename
putStrLn source
let parsed = parseSource source
putStrLn $ "[info] parsed words:\n" ++ show parsed
putStrLn "[info] interpreter output:"
interpretSource [] parsed
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