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Fix Foldable1 (NonEmpty f) instance #39

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Fix Foldable1 (NonEmpty f) instance #39

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64be837
Fix `Foldable1 (NonEmpty f)` instance
rhendric Oct 22, 2020
4e36320
fixup! Fix `Foldable1 (NonEmpty f)` instance
rhendric Oct 22, 2020
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4 changes: 3 additions & 1 deletion src/Data/NonEmpty.purs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ import Data.Eq (class Eq1)
import Data.Foldable (class Foldable, foldl, foldr, foldMap)
import Data.FoldableWithIndex (class FoldableWithIndex, foldMapWithIndex, foldlWithIndex, foldrWithIndex)
import Data.FunctorWithIndex (class FunctorWithIndex, mapWithIndex)
import Data.Maybe (Maybe(..))
import Data.Maybe (Maybe(..), maybe)
import Data.Ord (class Ord1)
import Data.Semigroup.Foldable (class Foldable1, foldMap1)
import Data.Traversable (class Traversable, traverse, sequence)
Expand Down Expand Up @@ -107,6 +107,8 @@ instance traversableWithIndexNonEmpty
instance foldable1NonEmpty :: Foldable f => Foldable1 (NonEmpty f) where
fold1 = foldMap1 identity
foldMap1 f (a :| fa) = foldl (\s a1 -> s <> f a1) (f a) fa
foldr1 f (a :| fa) = maybe a (f a) $ foldr (\a1 -> Just <<< maybe a1 (f a1)) Nothing fa
foldl1 = foldl1

instance unfoldable1NonEmpty :: Unfoldable f => Unfoldable1 (NonEmpty f) where
unfoldr1 f b = uncurry (:|) $ unfoldr (map f) <$> f b
5 changes: 3 additions & 2 deletions test/Main.purs
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Expand Up @@ -5,7 +5,7 @@ import Prelude
import Data.Foldable (fold, foldl)
import Data.Maybe (Maybe(..))
import Data.NonEmpty (NonEmpty, (:|), foldl1, oneOf, head, tail, singleton)
import Data.Semigroup.Foldable (fold1)
import Data.Semigroup.Foldable (fold1, foldr1)
import Data.Unfoldable1 as U1
import Effect (Effect)
import Test.Assert (assert)
Expand All @@ -19,7 +19,8 @@ main :: Effect Unit
main = do
assert $ singleton 0 == 0 :| []
assert $ 0 :| Nothing /= 0 :| Just 1
assert $ foldl1 (+) (1 :| [2, 3]) == 6
assert $ foldl1 (\l r -> "(" <> l <> r <> ")") ("a" :| ["b", "c", "d"]) == "(((ab)c)d)"
assert $ foldr1 (\l r -> "(" <> l <> r <> ")") ("a" :| ["b", "c", "d"]) == "(a(b(cd)))"
assert $ foldl (+) 0 (1 :| [2, 3]) == 6
assert $ fold1 ("Hello" :| [" ", "World"]) == "Hello World"
assert $ fold ("Hello" :| [" ", "World"]) == "Hello World"
Expand Down