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| author | David Luposchainsky <dluposchainsky@gmail.com> | 2017-08-11 12:56:32 +0200 |
|---|---|---|
| committer | Ben Gamari <ben@smart-cactus.org> | 2017-08-17 16:42:55 -0400 |
| commit | f762181ec0f48f1af9dd6d367f2a521d13988808 (patch) | |
| tree | 26c15b193144c88375fccd3f875fb9380ed92b5e | |
| parent | 63397cb3c51c4871990d120b2eaeba2f82729481 (diff) | |
| download | haskell-f762181ec0f48f1af9dd6d367f2a521d13988808.tar.gz | |
Mention the category laws explicitly
| -rw-r--r-- | libraries/base/Control/Category.hs | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/libraries/base/Control/Category.hs b/libraries/base/Control/Category.hs index ba92178bae..6407a6f509 100644 --- a/libraries/base/Control/Category.hs +++ b/libraries/base/Control/Category.hs @@ -28,8 +28,13 @@ import GHC.Prim (coerce) infixr 9 . infixr 1 >>>, <<< --- | A class for categories. --- id and (.) must form a monoid. +-- | A class for categories. Instances should satisfy the laws +-- +-- @ +-- f '.' 'id' = f -- (right identity) +-- 'id' '.' f = f -- (left identity) +-- f '.' (g '.' h) = (f '.' g) '.' h -- (associativity) +-- @ class Category cat where -- | the identity morphism id :: cat a a |