never executed always true always false

    1 module HelVM.HelIO.ListLike.ListLikeSafe where
    2 
    3 import           HelVM.HelIO.ListLike.ListLikeMay
    4 
    5 import           HelVM.HelIO.Control.Safe
    6 
    7 import           Data.ListLike
    8 
    9 import           Prelude                          hiding (break, divMod, drop, fromList, init, last, length, null, splitAt, swap, toList, uncons)
   10 
   11 -- | Construction
   12 convert :: (ListLike full1 item , ListLike full2 item) => full1 -> full2
   13 convert = fromList <$> toList
   14 
   15 maybeToFromList :: ListLike full item => Maybe item -> full
   16 maybeToFromList (Just e) = singleton e
   17 maybeToFromList Nothing  = mempty
   18 
   19 -- | Split
   20 splitBy :: (Eq item , ListLike full item) => item -> full -> (full , full)
   21 splitBy separator l =  (acc , drop 1 l') where (acc , l') = break (== separator) l
   22 
   23 -- | Pop
   24 discard :: (MonadSafe m , ListLike full item) => full -> m full
   25 discard l = appendError "Error for discard" $ snd <$> unconsSafe l
   26 
   27 top :: (MonadSafe m , ListLike full item) => full -> m item
   28 top s = appendError "Error for top" $ fst <$> unconsSafe s
   29 
   30 unconsSafe :: (MonadSafe m , ListLike full item) => full -> m (item , full)
   31 unconsSafe = liftMaybeOrError "Empty ListLike for unconsSafe" <$> uncons
   32 
   33 uncons2Safe :: (MonadSafe m , ListLike full item) => full -> m (item , item , full)
   34 uncons2Safe = liftMaybeOrError "Empty ListLike for uncons2Safe" <$> uncons2
   35 
   36 unsnocSafe :: (MonadSafe m , ListLike full item) => full -> m (full , item)
   37 unsnocSafe = liftMaybeOrError "Empty ListLike for unsnocSafe" <$> unsnoc