mirror of
https://github.com/idris-lang/Idris2.git
synced 2024-12-26 13:11:30 +03:00
20 lines
656 B
Idris
20 lines
656 B
Idris
import Data.List
|
|
import Data.String
|
|
|
|
byLength : Nat -> String -> Maybe (String, Nat)
|
|
byLength n str = (str, n) <$ guard (String.length str == n)
|
|
|
|
bySuccess : a -> (a -> Maybe b) -> Maybe b
|
|
bySuccess = flip ($)
|
|
|
|
-- cheating to display the remaining (const Nothing) function in 3rd case
|
|
Show b => Show (List a -> b) where
|
|
show f = "\\ _ => " ++ show (f [])
|
|
|
|
main : IO ()
|
|
main = putStr $ unlines
|
|
[ show $ prefixOfBy byLength [5,5,1] ["hello", "world", "!", "Not", "seen"]
|
|
, show $ suffixOfBy byLength [3,4] ["hello", "world", "!", "Not", "seen"]
|
|
, show $ prefixOfBy bySuccess [[1],[1,2],[]] [head', head' <=< tail', const (pure 3), const Nothing]
|
|
]
|