never executed always true always false

    1 module HelVM.HelIO.Digit.Digits (
    2   digitsToIntegral,
    3   naturalToDigits7,
    4   naturalToDigits2,
    5   naturalToDigits,
    6 ) where
    7 
    8 import qualified Data.ListLike                 as LL
    9 import           HelVM.HelIO.Collections.SList
   10 import           HelVM.HelIO.Control.Safe
   11 
   12 digitsToIntegral :: (MonadSafe m , Integral a) => a -> SList (m a) -> m a
   13 digitsToIntegral base = foldr (liftedMulAndAdd base) (pure 0)
   14 
   15 liftedMulAndAdd :: (MonadSafe m , Integral a)  => a -> m a -> m a -> m a
   16 liftedMulAndAdd base = liftA2 (mulAndAdd base)
   17 
   18 mulAndAdd :: Integral a => a -> a -> a -> a
   19 mulAndAdd base digit acc = acc * base + digit
   20 
   21 ----
   22 
   23 naturalToDigits7 :: Natural -> [Natural]
   24 naturalToDigits7 = naturalToDigits 7
   25 
   26 naturalToDigits2 :: Natural -> [Natural]
   27 naturalToDigits2 = naturalToDigits 2
   28 
   29 naturalToDigits :: Natural -> Natural -> [Natural]
   30 naturalToDigits base = LL.reverse <$> unfoldr (modDivMaybe base)
   31 
   32 modDivMaybe :: Natural -> Natural -> Maybe (Natural , Natural)
   33 modDivMaybe _    0     = Nothing
   34 modDivMaybe base value = Just (swap $ value `divMod` base)