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map :: forall f a b. Functor f => (a -> b) -> f a -> f b

Map k v represents maps from keys of type k to values of type v.

map :: forall a b. Ord b => (a -> b) -> Set a -> Set b

Maps over the values in a set.

This operation is not structure-preserving for sets, so is not a valid Functor. An example case: mapping const x over a set with n > 0 elements will result in a set with one element.

map :: forall a b. Ord b => (a -> b) -> NonEmptySet a -> NonEmptySet b

Maps over the values in a set.

This operation is not structure-preserving for sets, so is not a valid Functor. An example case: mapping const x over a set with n > 0 elements will result in a set with one element.

mapEnv :: forall e a b. (a -> b) -> Env e a -> Env e b

Change the data type in an Env computation.

mapRWS :: forall r w1 w2 s a1 a2. (RWSResult s a1 w1 -> RWSResult s a2 w2) -> RWS r w1 s a1 -> RWS r w2 s a2

Change the types of the result and accumulator in a RWS action

mapCont :: forall r a. (r -> r) -> Cont r a -> Cont r a

Transform the result of a continuation-passing function.

mapEnvT :: forall e w1 w2 a b. (w1 a -> w2 b) -> EnvT e w1 a -> EnvT e w2 b

Change the underlying comonad and data type in an EnvT context.

mapRWST :: forall r w1 w2 s m1 m2 a1 a2. (m1 (RWSResult s a1 w1) -> m2 (RWSResult s a2 w2)) -> RWST r w1 s m1 a1 -> RWST r w2 s m2 a2

Change the result and accumulator types in a RWST monad action.

mapping :: forall a b f. Mapping f a b => f -> a -> b

mapping :: forall s t a b f g. Functor f => Functor g => AnIso s t a b -> Iso (f s) (g t) (f a) (g b)

mapMaybe :: forall a b. (a -> Maybe b) -> List a -> List b

Apply a function to each element in a list, keeping only the results which contain a value.

Running time: O(n)

mapMaybe :: forall a b. (a -> Maybe b) -> List a -> List b

Apply a function to each element in a list, keeping only the results which contain a value.

Running time: O(n)

mapMaybe :: forall a b. (a -> Maybe b) -> NonEmptyList a -> List b

mapMaybe :: forall a b. (a -> Maybe b) -> Array a -> Array b

Apply a function to each element in an array, keeping only the results which contain a value, creating a new array.

parseEmail :: String -> Maybe Email
parseEmail = ...

mapMaybe parseEmail ["a.com", "hello@example.com", "--"]
   = [Email {user: "hello", domain: "example.com"}]

mapMaybe :: forall a b. (a -> Maybe b) -> NonEmptyArray a -> Array b

mapMaybe :: forall k a b. Ord k => (a -> Maybe b) -> Map k a -> Map k b

Applies a function to each value in a map, discarding entries where the function returns Nothing.

mapMaybe :: forall a b. Ord b => (a -> Maybe b) -> Set a -> Set b

Applies a function to each value in a set, discarding entries where the function returns Nothing.

mapMaybe :: forall a b. Ord b => (a -> Maybe b) -> NonEmptySet a -> Set b

Applies a function to each value in a set, discarding entries where the function returns Nothing.

mapContT :: forall r m a. (m r -> m r) -> ContT r m a -> ContT r m a

Modify the underlying action in a ContT monad action.

mapMaybe :: forall f a b. Functor f => (a -> Maybe b) -> ListT f a -> ListT f b

Apply a function to the elements of a list, keeping only those return values which contain a result.

mapState :: forall s a b. (Tuple a s -> Tuple b s) -> State s a -> State s b

Change the type of the result in a State action

mapMaybe :: forall k a b. (a -> Maybe b) -> Map k a -> Map k b

Applies a function to each value in a map, discarding entries where the function returns Nothing.

mapReply :: forall state reply mappedReply. (reply -> mappedReply) -> Effect (RestResult reply state) -> Effect (RestResult mappedReply state)

mapAccumL :: forall a b s f. Traversable f => (s -> a -> Accum s b) -> s -> f a -> Accum s (f b)

Fold a data structure from the left, keeping all intermediate results instead of only the final result.

Unlike scanl, mapAccumL allows the type of accumulator to differ from the element type of the final data structure.

mapAccumR :: forall a b s f. Traversable f => (s -> a -> Accum s b) -> s -> f a -> Accum s (f b)

Fold a data structure from the right, keeping all intermediate results instead of only the final result.

Unlike scanr, mapAccumR allows the type of accumulator to differ from the element type of the final data structure.

mapExcept :: forall e e' a b. (Either e a -> Either e' b) -> Except e a -> Except e' b

Transform the unwrapped computation using the given function.

mapMaybeT :: forall m1 m2 a b. (m1 (Maybe a) -> m2 (Maybe b)) -> MaybeT m1 a -> MaybeT m2 b

Change the result type of a MaybeT monad action.

mapReader :: forall r a b. (a -> b) -> Reader r a -> Reader r b

Change the type of the result in a Reader monad action.

mapStateT :: forall s m1 m2 a b. (m1 (Tuple a s) -> m2 (Tuple b s)) -> StateT s m1 a -> StateT s m2 b

Change the result type in a StateT monad action.

mapWriter :: forall w1 w2 a b. (Tuple a w1 -> Tuple b w2) -> Writer w1 a -> Writer w2 b

Change the result and accumulator types in a Writer monad action

mapFlipped :: forall f a b. Functor f => f a -> (a -> b) -> f b

mapFlipped is map with its arguments reversed. For example:

[1, 2, 3] <#> \n -> n * n

mapDefault :: forall i f a b. FunctorWithIndex i f => (a -> b) -> f a -> f b

A default implementation of Functor's map in terms of mapWithIndex

mapExceptT :: forall e e' m n a b. (m (Either e a) -> n (Either e' b)) -> ExceptT e m a -> ExceptT e' n b

Transform the unwrapped computation using the given function.

mapReaderT :: forall r m1 m2 a b. (m1 a -> m2 b) -> ReaderT r m1 a -> ReaderT r m2 b

Change the type of the result in a ReaderT monad action.

mapWriterT :: forall w1 w2 m1 m2 a b. (m1 (Tuple a w1) -> m2 (Tuple b w2)) -> WriterT w1 m1 a -> WriterT w2 m2 b

Change the accumulator and base monad types in a WriterT monad action.

mapWithKey :: forall k a b. (k -> a -> b) -> Map k a -> Map k b

mapParserT :: forall b n s a m. (m (Tuple (Either ParseError a) (ParseState s)) -> n (Tuple (Either ParseError b) (ParseState s))) -> ParserT s m a -> ParserT s n b

Change the underlying monad action and data type in a ParserT monad action.

mapWithIndex :: forall f i a b. FunctorWithIndex i f => (i -> a -> b) -> f a -> f b

mapWithIndex :: forall a b. (Int -> a -> b) -> List a -> List b

Apply a function to each element and its index in a list starting at 0.

Deprecated. Use Data.FunctorWithIndex instead.

mapWithIndex :: forall a b. (Int -> a -> b) -> NonEmptyList a -> NonEmptyList b

Apply a function to each element and its index in a list starting at 0.

Deprecated. Use Data.FunctorWithIndex instead.

mapWithIndex :: forall a b. (Int -> a -> b) -> Array a -> Array b

Apply a function to each element in an array, supplying a generated zero-based index integer along with the element, creating an array with the new elements.

prefixIndex index element = show index <> element

mapWithIndex prefixIndex ["Hello", "World"] = ["0Hello", "1World"]

mapWithIndex :: forall a b. (Int -> a -> b) -> NonEmptyArray a -> NonEmptyArray b

mapIdentityT :: forall m1 m2 a b. (m1 a -> m2 b) -> IdentityT m1 a -> IdentityT m2 b

Change the result type of a IdentityT monad action.

mapMaybeWithKey :: forall k a b. Ord k => (k -> a -> Maybe b) -> Map k a -> Map k b

Applies a function to each key/value pair in a map, discarding entries where the function returns Nothing.

mapMaybeWithKey :: forall k a b. (k -> a -> Maybe b) -> Map k a -> Map k b

Applies a function to each key/value pair in a map, discarding entries where the function returns Nothing.