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devyn/bfLike.hs

Created May 30, 2010 02:26
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bfLike.hs
module BFLike
(run, interpret, tobc, eval) where
import Data.Char
qqq :: (a, b, c) -> d -> (a, b, c, d)
qqq (a, b, c) d = (a, b, c, d)
run' :: ([Char], [Int], Int) -> Int -> ([Char], [Int], Int)
run' (value, state, ptr) inst =
case inst of
1 -> (value, (take ptr state) ++ [(state !! ptr) + 1] ++ (drop (ptr + 1) state), ptr)
2 -> (value, (take ptr state) ++ [(state !! ptr) - 1] ++ (drop (ptr + 1) state), ptr)
3 -> (value, if length state == ptr + 1 then state ++ [0] else state, ptr + 1)
4 -> (value, state, ptr - 1)
5 -> (value ++ [chr $ state !! ptr], state, ptr)
while :: ([Char], [Int], Int, (Bool, [Int])) -> ([Char], [Int], Int, (Bool, [Int]))
while (value, state, ptr, rc) =
if state' !! ptr' < 1
then (value', state', ptr', (False, []))
else while (value', state', ptr', rc)
where (value', state', ptr', rc') = foldl run (value, state, ptr, (False, [])) (snd rc)
run :: ([Char], [Int], Int, (Bool, [Int])) -> Int -> ([Char], [Int], Int, (Bool, [Int]))
run (value, state, ptr, rc) inst =
if fst rc
then
case inst of
7 -> while (value, state, ptr, (False, snd rc))
_ -> (value, state, ptr, (True, (snd rc) ++ [inst]))
else
case inst of
6 -> (value, state, ptr, (True, []))
_ -> qqq (run' (value, state, ptr) inst) rc
interpret :: [Int] -> [Char]
interpret l = value where (value, state, ptr, rc) = foldl run ([], [0], 0, (False, [])) l
tobc :: [Char] -> [Int]
tobc = map $ \c-> case c of
'+' -> 1
'-' -> 2
'>' -> 3
'<' -> 4
'.' -> 5
'[' -> 6
']' -> 7
eval :: [Char] -> [Char]
eval = interpret . tobc
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