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|
module Binary
( toBinary
, fromBinary
, toBitString
, fromBitString
) where
import Control.Applicative
import qualified Data.BitString as Bit
import Data.Char
import Helper
toBinary :: Expression -> String
toBinary (Bruijn x ) = (replicate (x + 1) '1') ++ "0"
toBinary (Abstraction exp ) = "00" ++ toBinary exp
toBinary (Application exp1 exp2) = "01" ++ (toBinary exp1) ++ (toBinary exp2)
-- Stolen from John Tromp
fromBinary :: String -> Expression
fromBinary = foldr
(\x -> Abstraction . (Application . Application (Bruijn 0) . code $ x))
nil
where
nil = code '1'
code '0' = Abstraction (Abstraction (Bruijn 1))
code '1' = Abstraction (Abstraction (Bruijn 0))
code x = fromBinary (showsBin 8 (ord x) "")
showsBin n x = if n == 0
then id
else let (x', b) = divMod x 2 in showsBin (n - 1) x' . (intToDigit b :)
-- TODO: Fix weird endianess things
padBitList :: [Bool] -> [Bool]
padBitList lst | length lst `mod` 8 == 0 = lst
| otherwise = padBitList ([False] ++ lst)
toBitString :: String -> Bit.BitString
toBitString = Bit.fromList . padBitList . map
(\case
'0' -> False
'1' -> True
)
fromBitString :: Bit.BitString -> String
fromBitString =
map
(\case
False -> '0'
True -> '1'
)
. Bit.toList
|
