. is:exact - Hoogle

Right to left function composition.

(f . g) x = f (g x)

f . id = f = id . f

Examples

>>> map ((*2) . length) [[], [0, 1, 2], [0]]
[0,6,2]

>>> foldr (.) id [(+1), (*3), (^3)] 2
25

>>> let (...) = (.).(.) in ((*2)...(+)) 5 10
30

(.) :: forall (b :: k) (c :: k) (a :: k) . Category cat => cat b c -> cat a b -> cat a c

base Control.Category, ghc-internal GHC.Internal.Control.Category, verset Verset

Morphism composition. Implementations should satisfy the law:

Associativity f . (g . h) = (f . g) . h

This means that the way morphisms are grouped is irrelevant, so it is unambiguous to write a composition of morphisms as f . g . h, without parentheses.

(.) :: (b -> c) -> (a -> b) -> a -> c

Function composition.

(.) :: (b -> c) -> (a -> b) -> a -> c

ghc GHC.Prelude.Basic

(.) :: forall (b :: k) (c :: k) (a :: k) . Category cat => cat b c -> cat a b -> cat a c

base-prelude BasePrelude, classy-prelude ClassyPrelude, basement Basement.Compat.Base Basement.Imports, foundation Foundation, dimensional Numeric.Units.Dimensional.Prelude, rebase Rebase.Prelude, quaalude Essentials

morphism composition

(.) :: Category k cat => forall (b :: k) (c :: k) (a :: k) . cat b c -> cat a b -> cat a c

basic-prelude CorePrelude

morphism composition

(.) :: JExpr -> String -> JExpr

jmacro Language.Javascript.JMacro.Util

(.) :: () => (b -> c) -> (a -> b) -> a -> c

prelude-compat Prelude2010

Function composition.

(.) :: (Category k, Object k a, Object k b, Object k c) => k b c -> k a b -> k a c

constrained-categories Control.Category.Constrained Control.Category.Constrained.Prelude

(.) :: (b <-> c) -> (a <-> b) -> a <-> c

invertible Data.Invertible.Function Data.Invertible.Prelude

Bijection composition

(.) :: Category cat => cat b c -> cat a b -> cat a c

free-categories Control.Category.Free

morphism composition

(.) :: (b -> c) -> (a -> b) -> a -> c

between Data.Function.Between.Strict.Internal

Strict variant of function composition. Defined as:

(f . g) x = f $! g $! x

Internally used since version 0.10.0.0. Moved to Data.Function.Between.Strict.Internal module and exposed in version 0.11.0.0.