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

Language | Haskell98 |

This module is for convenience and demonstrative purposes more than it is for providing actual value. I do not recommend that you rely on this module for performance-sensitive code. Because this module is not based on Prelude's (.), some chances at optimization might be missed by your compiler.

- (∘) :: (b -> c) -> (a -> b) -> a -> c
- (.:) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
- (.:.) :: (d -> e) -> (a -> b -> c -> d) -> a -> b -> c -> e
- (.::) :: (d -> e) -> (a -> a1 -> b -> c -> d) -> a -> a1 -> b -> c -> e
- (.::.) :: (d -> e) -> (a -> a1 -> a2 -> b -> c -> d) -> a -> a1 -> a2 -> b -> c -> e
- (.:::) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e
- (.:::.) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e
- (.::::) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> e
- (.::::.) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> e
- (.*) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
- (.**) :: (d -> e) -> (a -> b -> c -> d) -> a -> b -> c -> e
- (.***) :: (d -> e) -> (a -> a1 -> b -> c -> d) -> a -> a1 -> b -> c -> e
- (.****) :: (d -> e) -> (a -> a1 -> a2 -> b -> c -> d) -> a -> a1 -> a2 -> b -> c -> e
- (.*****) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e
- (.******) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e
- (.*******) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> e
- (.********) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> e
- compose1 :: (b -> c) -> (a -> b) -> a -> c
- compose2 :: (c -> d) -> (a -> b -> c) -> a -> b -> d
- compose3 :: (d -> e) -> (a -> b -> c -> d) -> a -> b -> c -> e
- compose4 :: (d -> e) -> (a -> a1 -> b -> c -> d) -> a -> a1 -> b -> c -> e
- compose5 :: (d -> e) -> (a -> a1 -> a2 -> b -> c -> d) -> a -> a1 -> a2 -> b -> c -> e
- compose6 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e
- compose7 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e
- compose8 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> e
- compose9 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> e

# Math

(∘) :: (b -> c) -> (a -> b) -> a -> c infixr 9 Source

The mathematical symbol for function composition.

# Colons and dots

(.:) :: (c -> d) -> (a -> b -> c) -> a -> b -> d infixr 8 Source

Compose two functions. `f .: g`

is similar to `f . g`

except that `g`

will be fed *two* arguments instead of one
before handing its result to `f`

.

This function is defined as

(f .: g) x y = f (g x y)

Example usage:

concatMap :: (a -> b) -> [a] -> [b] concatMap = concat .: map

Notice how *two* arguments
(the function *and* the list)
will be given to `map`

before the result
is passed to `concat`

. This is equivalent to:

concatMap f xs = concat (map f xs)

(.:.) :: (d -> e) -> (a -> b -> c -> d) -> a -> b -> c -> e infixr 8 Source

One compact pattern for composition operators is to
"count the dots after the first one",
which begins with the common `.:`

, and proceeds by first
appending another `.`

and then replacing it with `:`

(.::.) :: (d -> e) -> (a -> a1 -> a2 -> b -> c -> d) -> a -> a1 -> a2 -> b -> c -> e infixr 8 Source

(.:::) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e infixr 8 Source

(.:::.) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e infixr 8 Source

(.::::) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> e infixr 8 Source

(.::::.) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> e infixr 8 Source

# Asterisks

(.*) :: (c -> d) -> (a -> b -> c) -> a -> b -> d infixr 8 Source

Equivalent to `.:`

The pattern of appending asterisks is
straightforward to extend to similar functions:
(compose2 = .*, compose3 = .**, etc).
However, `.:`

has been commonly adopted amongst Haskellers,
and the need for compose3 and beyond is rare in practice.

(.****) :: (d -> e) -> (a -> a1 -> a2 -> b -> c -> d) -> a -> a1 -> a2 -> b -> c -> e infixr 8 Source

(.*****) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e infixr 8 Source

(.******) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e infixr 8 Source

(.*******) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> b -> c -> e infixr 8 Source

(.********) :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> a5 -> a6 -> b -> c -> e infixr 8 Source

# composeN

compose1 :: (b -> c) -> (a -> b) -> a -> c Source

`composeN f g`

means give `g`

`N`

inputs
and then pass its result to `f`

.

compose6 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> b -> c -> e Source

compose7 :: (d -> e) -> (a -> a1 -> a2 -> a3 -> a4 -> b -> c -> d) -> a -> a1 -> a2 -> a3 -> a4 -> b -> c -> e Source