Relude.Extra.Tuple

Contains utility functions for working with tuples.

Since: 0.4.0

Documentation

dup :: a -> (a, a)

Creates a tuple by pairing something with itself.

>>> dup "foo"
("foo","foo")
>>> dup ()
((),())

Since: 0.6.0.0

toFst :: (a -> b) -> a -> (b, a)

Apply a function, with the result in the fst slot, and the value in the other.

A dual to toSnd.

>>> toFst length [3, 1, 0, 2]
(4,[3,1,0,2])
>>> toFst (+5) 10
(15,10)

Since: 0.7.0.0

toSnd :: (a -> b) -> a -> (a, b)

Apply a function, with the result in the snd slot, and the value in the other.

A dual to toFst.

>>> toSnd length [3, 1, 0, 2]
([3,1,0,2],4)
>>> toSnd (+5) 10
(10,15)

Since: 0.7.0.0

fmapToFst :: Functor f => (a -> b) -> f a -> f (b, a)

Like fmap, but also keep the original value in the snd position.

A dual to fmapToSnd.

>>> fmapToFst show [3, 10, 2]
[("3",3),("10",10),("2",2)]

Since: 0.7.0.0

fmapToSnd :: Functor f => (a -> b) -> f a -> f (a, b)

Like fmap, but also keep the original value in the fst position.

A dual to fmapToFst.

>>> fmapToSnd show [3, 10, 2]
[(3,"3"),(10,"10"),(2,"2")]

Since: 0.7.0.0

mapToFst :: (a -> b) -> a -> (b, a)

Deprecated: Use toFst from Tuple instead

Apply a function, with the result in the fst slot, and the value in the other.

A dual to mapToSnd

>>> mapToFst (+1) 10
(11,10)

Since: 0.4.0

mapToSnd :: (a -> b) -> a -> (a, b)

Deprecated: Use toSnd from Tuple instead

Apply a function, with the result in the second slot, and the value in the other.

A dual to mapToFst.

>>> mapToSnd (+1) 10
(10,11)

Since: 0.4.0

traverseToFst :: Functor t => (a -> t b) -> a -> t (b, a)

Apply a function that returns a value inside of a functor, with the output in the first slot, the input in the second, and the entire tuple inside the functor.

A dual to traverseToSnd

>>> traverseToFst (Just . (+1)) 10
Just (11,10)
>>> traverseToFst (const Nothing) 10
Nothing

Since: 0.5.0

traverseToSnd :: Functor t => (a -> t b) -> a -> t (a, b)

Apply a function that returns a value inside of a functor, with the output in the second slot, the input in the first, and the entire tuple inside the functor.

A dual to traverseToFst.

>>> traverseToSnd (Just . (+1)) 10
Just (10,11)
>>> traverseToSnd (const Nothing) 10
Nothing

Since: 0.5.0

traverseBoth :: Applicative t => (a -> t b) -> (a, a) -> t (b, b)

Maps a function that returns a value inside of an applicative functor over both elements of a tuple, with the entire tuple inside the applicative functor.

>>> traverseBoth (Just . ("Hello " <>)) ("Alice", "Bob")
Just ("Hello Alice","Hello Bob")
>>> traverseBoth (const Nothing) ("Alice", "Bob")
Nothing