lude

Haskell prelude alternative
git clone git://git.rr3.xyz/lude | git clone gits://git.rr3.xyz/lude
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List.hs (552B)

      1 module Lude.List (
      2     List,
      3     index,
      4     ( #? ),
      5 ) where
      6 
      7 import Lude.Haskell
      8 import Lude.Haskell.List (List)
      9 import Lude.Maybe
     10 import Lude.Natural
     11 
     12 -- TODO: pindex, (!!) :: (Partial) => ...
     13 
     14 -- TODO: Somehow generalize indices beyond Natural (e.g., Nat64 should also work?)
     15 
     16 --------------------------------------------------------------------------------
     17 
     18 index, ( #? ) :: forall (a :: Type). List a -> Natural -> Maybe a
     19 index [] _ = Nothing
     20 index (h : _) NaturalZero = Just h
     21 index (_ : t) (NaturalSucc n) = index t n
     22 ( #? ) = index
     23 infixl 9 #?