Safe Haskell | Safe |
---|---|

Language | Haskell2010 |

Extra functions for working with pairs and triples. Some of these functions are available in the Control.Arrow module, but here are available specialised to pairs. Some operations work on triples.

## Synopsis

- module Data.Tuple
- first :: (a -> a') -> (a, b) -> (a', b)
- second :: (b -> b') -> (a, b) -> (a, b')
- (***) :: (a -> a') -> (b -> b') -> (a, b) -> (a', b')
- (&&&) :: (a -> b) -> (a -> c) -> a -> (b, c)
- dupe :: a -> (a, a)
- both :: (a -> b) -> (a, a) -> (b, b)
- firstM :: Functor m => (a -> m a') -> (a, b) -> m (a', b)
- secondM :: Functor m => (b -> m b') -> (a, b) -> m (a, b')
- fst3 :: (a, b, c) -> a
- snd3 :: (a, b, c) -> b
- thd3 :: (a, b, c) -> c
- curry3 :: ((a, b, c) -> d) -> a -> b -> c -> d
- uncurry3 :: (a -> b -> c -> d) -> (a, b, c) -> d

# Documentation

module Data.Tuple

# Specialised `Arrow`

functions

first :: (a -> a') -> (a, b) -> (a', b) Source #

Update the first component of a pair.

first succ (1,"test") == (2,"test")

second :: (b -> b') -> (a, b) -> (a, b') Source #

Update the second component of a pair.

second reverse (1,"test") == (1,"tset")

(***) :: (a -> a') -> (b -> b') -> (a, b) -> (a', b') infixr 3 Source #

Given two functions, apply one to the first component and one to the second.
A specialised version of `***`

.

(succ *** reverse) (1,"test") == (2,"tset")

(&&&) :: (a -> b) -> (a -> c) -> a -> (b, c) infixr 3 Source #

Given two functions, apply both to a single argument to form a pair.
A specialised version of `&&&`

.

(succ &&& pred) 1 == (2,0)

# More pair operations

both :: (a -> b) -> (a, a) -> (b, b) Source #

Apply a single function to both components of a pair.

both succ (1,2) == (2,3)

# Monadic versions

firstM :: Functor m => (a -> m a') -> (a, b) -> m (a', b) Source #

Update the first component of a pair.

firstM (\x -> [x-1, x+1]) (1,"test") == [(0,"test"),(2,"test")]

secondM :: Functor m => (b -> m b') -> (a, b) -> m (a, b') Source #

Update the second component of a pair.

secondM (\x -> [reverse x, x]) (1,"test") == [(1,"tset"),(1,"test")]