663f565 · elk · git.iko.soy

Add a filter function

Bring Array library more in line with Dict and Set which now have this function as well.

commit663f5652c6793b1824d5977e16d8ba5ff51099c3 authorEvan Czaplicki <info@elm-lang.org> dateWed 16 Apr 2014, 16:29 (13 years ago) parent3fb4ea1

2 files changed+11

unifiedsplit

libraries/Array.elm+10

@@ -96,6 +96,16 @@ foldl = Native.Array.foldl

9696foldr : (a -> b -> b) -> b -> Array a -> b

9797foldr = Native.Array.foldr

9898

99+{-| Keep only elements that satisfy the predicate:

100+

101+ filter isEven (fromList [1..6]) == (fromList [2,4,6])

102+-}

103+filter : (a -> Bool) -> Array a -> Array a

104+filter isOkay arr =

105+ let update x xs = if isOkay x then Native.Array.push x xs else xs

106+ in

107+ Native.Array.foldl update Native.Array.empty arr

108+

99109{-| Return an empty array.

100110

101111 length empty == 0

tests/elm/Test/Array.elm+1

@@ -43,5 +43,6 @@ tests =

4343 , test "foldl" <| assertEqual (Array.foldl (::) [] (Array.fromList [1,2,3])) [3,2,1]

4444 , test "foldr" <| assertEqual (Array.foldr (+) 0 (Array.repeat 3 5)) 15

4545 , test "foldr 2" <| assertEqual (Array.foldr (::) [] (Array.fromList [1,2,3])) [1,2,3]

46+ , test "filter" <| assertEqual (Array.filter (\x -> x `mod` 2 == 0) (Array.fromList [1..6])) (Array.fromList [2,4,6])

4647 ]

4748 in List.concat [creationTests, basicsTests, getAndSetTests, takingArraysApartTests, mappingAndFoldingTests]