HaskellFuck

README.md

HaskellFuck

Compile

ghc bf.hs

Hello World

cat hello | ./a.out

bf.hs

import Data.Char

class Mem a where
    empty :: a
    
instance Mem Int where empty = 0    
instance Mem Char where empty = ' '
    
data (Mem a) => Tape a = Tape Int [a] deriving (Show)
    
get (Tape 0 (x:_)) = x
get (Tape i (x:xs)) = get $ Tape (i - 1) xs

set (Tape i xs) n = Tape i $ a ++ (n:b)
    where   a = fst tape
            b = tail $ snd tape
            tape = splitAt i xs            

next (Tape i xs)
    | i < length xs - 1 = Tape (i + 1) xs
    | otherwise         = Tape (i + 1) (xs ++ [empty])
    
prev (Tape i xs)
    | i < 1     = Tape i (empty:xs)
    | otherwise = Tape (i - 1) xs
    
incr tape = set tape $ (get tape) + 1

decr tape = set tape $ (get tape) - 1

exec instruction memory
    | command == '>' = exec (next instruction) (next memory)
    | command == '<' = exec (next instruction) (prev memory)
    | command == '+' = exec (next instruction) (incr memory)
    | command == '-' = exec (next instruction) (decr memory)
    | command == '.' = do
        putChar $ (chr value)
        exec (next instruction) memory
    | command == ',' = do
        c <- getChar
        exec (next instruction) (set memory $ ord c)
    | command == '[' && value == 0 = exec (jumpTo instruction) memory
    | command == '[' && value /= 0 = exec (next instruction) memory
    | command == ']' && value /= 0 = exec (jumpBack instruction) memory
    | command == ']' && value == 0 = exec (next instruction) memory
    | otherwise      = return ()
    where   command  = get instruction
            value    = get memory                        
            jumpTo tape
                | get tape == ']'   = next tape
                | otherwise         = jumpTo $ next tape                    
            jumpBack tape
                | get tape == '['   = next tape
                | otherwise         = jumpBack $ prev tape

main = do
    inst <- getLine
    exec (Tape 0 inst) (Tape 0 [0])

hello

++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.