Copyright | (C) 2008-2014 Edward Kmett |
---|---|
License | BSD-style (see the file LICENSE) |
Maintainer | libraries@haskell.org |
Stability | provisional |
Portability | portable |
Safe Haskell | Safe |
Language | Haskell2010 |
Since: 4.8.0.0
- class Bifunctor p where
Documentation
class Bifunctor p where Source #
Formally, the class Bifunctor
represents a bifunctor
from Hask
-> Hask
.
Intuitively it is a bifunctor where both the first and second arguments are covariant.
You can define a Bifunctor
by either defining bimap
or by
defining both first
and second
.
If you supply bimap
, you should ensure that:
bimap
id
id
≡id
If you supply first
and second
, ensure:
first
id
≡id
second
id
≡id
If you supply both, you should also ensure:
bimap
f g ≡first
f.
second
g
These ensure by parametricity:
bimap
(f.
g) (h.
i) ≡bimap
f h.
bimap
g ifirst
(f.
g) ≡first
f.
first
gsecond
(f.
g) ≡second
f.
second
g
Since: 4.8.0.0
bimap :: (a -> b) -> (c -> d) -> p a c -> p b d Source #
Bifunctor Either Source # | Since: 4.8.0.0 |
Bifunctor (,) Source # | Since: 4.8.0.0 |
Bifunctor Arg Source # | Since: 4.9.0.0 |
Bifunctor ((,,) x1) Source # | Since: 4.8.0.0 |
Bifunctor (Const *) Source # | Since: 4.8.0.0 |
Bifunctor (K1 * i) Source # | Since: 4.9.0.0 |
Bifunctor ((,,,) x1 x2) Source # | Since: 4.8.0.0 |
Bifunctor ((,,,,) x1 x2 x3) Source # | Since: 4.8.0.0 |
Bifunctor ((,,,,,) x1 x2 x3 x4) Source # | Since: 4.8.0.0 |
Bifunctor ((,,,,,,) x1 x2 x3 x4 x5) Source # | Since: 4.8.0.0 |