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Document uncons/unsnoc.

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This commit is contained in:
Rob Rix 2016-03-14 09:17:26 -04:00
parent 564128a80a
commit 096680b668
1 changed files with 2 additions and 0 deletions
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src/Data/Adjoined.hs
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@ -14,10 +14,12 @@ newtype Adjoined a = Adjoined { unAdjoined :: Seq a }
fromList :: [a] -> Adjoined a
fromList = Adjoined . Seq.fromList
-- | Destructure a non-empty Adjoined into Just the leftmost element and the rightward remainder of the Adjoined, or Nothing otherwise.
uncons :: Adjoined a -> Maybe (a, Adjoined a)
uncons (Adjoined v) | a :< as <- viewl v = Just (a, Adjoined as)
| otherwise = Nothing
-- | Destructure a non-empty Adjoined into Just the rightmost element and the leftward remainder of the Adjoined, or Nothing otherwise.
unsnoc :: Adjoined a -> Maybe (Adjoined a, a)
unsnoc (Adjoined v) | as :> a <- viewr v = Just (Adjoined as, a)
| otherwise = Nothing