module Main where
import System.Posix.Resource
import Data.Char
import System.IO
import Language.Unlambda
main :: IO Exp
main = (setResourceLimit ResourceCPUTime $ ResourceLimits (ResourceLimit 5) (ResourceLimit 5)) >> run
run :: IO Exp
run = do
expr <- parse stdin
let (Eval cp) = eval expr
cp (Nothing, 2048) (const return)
parse :: Handle -> IO Exp
parse h = do
c <- catch (hGetChar h) (\_ -> error "Parse error at end of file")
case toLower c of
d | d `elem` " \t\n" -> parse h
'`' -> do e1 <- parse h
e2 <- parse h
return (App e1 e2)
'#' -> hGetLine h >> parse h
'.' -> hGetChar h >>= return . Dot
'?' -> hGetChar h >>= return . Ques
_ | Just fn <- lookup c table -> return fn
| otherwise -> error $ "Unknown operator " ++ show c
where table = zip "ksivcdre@|" [K,S,I,V,C,D,Dot '\n',E,At,Pipe]