mtlstats/src/Mtlstats/Util.hs
Jonathan Lamothe 3d705c4e6d implemented nth
2019-09-18 02:45:20 -04:00

30 lines
868 B
Haskell

{- |
mtlstats
Copyright (C) 2019 Rhéal Lamothe
<rheal.lamothe@gmail.com>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
-}
module Mtlstats.Util (nth) where
nth :: Int -> [a] -> Maybe a
nth _ [] = Nothing
nth n (x:xs)
| n == 0 = Just x
| n < 0 = Nothing
| otherwise = nth (pred n) xs