663f565 · elk · git.iko.soy

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Add a filter function

663f565Evan Czaplicki13 years ago

libraries/Array.elm+10

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

96foldr : (a -> b -> b) -> b -> Array a -> b

97foldr = Native.Array.foldr

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+

99{-| Return an empty array.

109{-| Return an empty array.

100

110

101 length empty == 0

111 length empty == 0

tests/elm/Test/Array.elm+1

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

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

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

45 , 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])

46 ]

47 ]

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

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