Add groupBy to Array.NonEmpty (#164)

Author: Zelenya

src/Data/Array/NonEmpty.purs

@@ -65,6 +65,9 @@ module Data.Array.NonEmpty
   , dropEnd
   , dropWhile
   , span
+  , group
+  , group'
+  , groupBy
 
   , nub
   , nubBy
@@ -347,6 +350,15 @@ span
   -> { init :: Array a, rest :: Array a }
 span f = adaptAny $ A.span f
 
+group :: forall a. Eq a => NonEmptyArray a -> NonEmptyArray (NonEmptyArray a)
+group = unsafeAdapt $ A.group
+
+group' :: forall a. Ord a => NonEmptyArray a -> NonEmptyArray (NonEmptyArray a)
+group' = unsafeAdapt $ A.group'
+
+groupBy :: forall a. (a -> a -> Boolean) -> NonEmptyArray a -> NonEmptyArray (NonEmptyArray a)
+groupBy op = unsafeAdapt $ A.groupBy op
+
 nub :: forall a. Ord a => NonEmptyArray a -> NonEmptyArray a
 nub = unsafeAdapt A.nub
 

test/Test/Data/Array/NonEmpty.purs

@@ -244,6 +244,18 @@ testNonEmptyArray = do
   let oneToSeven = fromArray [1, 2, 3, 4, 5, 6, 7]
   testSpan { p: (_ < 4), input: oneToSeven, init_: [1, 2, 3], rest_: [4, 5, 6, 7] }
 
+  log "group should group consecutive equal elements into arrays"
+  assert $ NEA.group (fromArray [1, 2, 2, 3, 3, 3, 1]) == fromArray [NEA.singleton 1, fromArray [2, 2], fromArray [3, 3, 3], NEA.singleton 1]
+
+  log "group' should sort then group consecutive equal elements into arrays"
+  assert $ NEA.group' (fromArray [1, 2, 2, 3, 3, 3, 1]) == fromArray [fromArray [1, 1], fromArray [2, 2], fromArray [3, 3, 3]]
+
+  log "groupBy should group consecutive equal elements into arrays based on an equivalence relation"
+  assert $ NEA.groupBy (\x y -> odd x && odd y) (fromArray [1, 1, 2, 2, 3, 3]) == fromArray [fromArray [1, 1], NEA.singleton 2, NEA.singleton 2, fromArray [3, 3]]
+
+  log "groupBy should be stable"
+  assert $ NEA.groupBy (\_ _ -> true) (fromArray [1, 2, 3]) == fromArray [fromArray [1, 2, 3]]
+
   log "nub should remove duplicate elements from the list, keeping the first occurence"
   assert $ NEA.nub (fromArray [1, 2, 2, 3, 4, 1]) == fromArray [1, 2, 3, 4]