base-4.9.1.0: Basic libraries

Data.Bifunctor

Description

Since: 4.8.0.0

Synopsis

# Documentation

class Bifunctor p where #

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 i
first  (f . g) ≡ first  f . first  g
second (f . g) ≡ second f . second g


Since: 4.8.0.0

Minimal complete definition

Methods

bimap :: (a -> b) -> (c -> d) -> p a c -> p b d #

Map over both arguments at the same time.

bimap f g ≡ first f . second g

first :: (a -> b) -> p a c -> p b c #

Map covariantly over the first argument.

first f ≡ bimap f id

second :: (b -> c) -> p a b -> p a c #

Map covariantly over the second argument.

second ≡ bimap id

Instances

 # Methodsbimap :: (a -> b) -> (c -> d) -> Either a c -> Either b d #first :: (a -> b) -> Either a c -> Either b c #second :: (b -> c) -> Either a b -> Either a c # # Methodsbimap :: (a -> b) -> (c -> d) -> (a, c) -> (b, d) #first :: (a -> b) -> (a, c) -> (b, c) #second :: (b -> c) -> (a, b) -> (a, c) # # Methodsbimap :: (a -> b) -> (c -> d) -> Arg a c -> Arg b d #first :: (a -> b) -> Arg a c -> Arg b c #second :: (b -> c) -> Arg a b -> Arg a c # Bifunctor (K1 i) # Methodsbimap :: (a -> b) -> (c -> d) -> K1 i a c -> K1 i b d #first :: (a -> b) -> K1 i a c -> K1 i b c #second :: (b -> c) -> K1 i a b -> K1 i a c # Bifunctor ((,,) x1) # Methodsbimap :: (a -> b) -> (c -> d) -> (x1, a, c) -> (x1, b, d) #first :: (a -> b) -> (x1, a, c) -> (x1, b, c) #second :: (b -> c) -> (x1, a, b) -> (x1, a, c) # # Methodsbimap :: (a -> b) -> (c -> d) -> Const * a c -> Const * b d #first :: (a -> b) -> Const * a c -> Const * b c #second :: (b -> c) -> Const * a b -> Const * a c # Bifunctor ((,,,) x1 x2) # Methodsbimap :: (a -> b) -> (c -> d) -> (x1, x2, a, c) -> (x1, x2, b, d) #first :: (a -> b) -> (x1, x2, a, c) -> (x1, x2, b, c) #second :: (b -> c) -> (x1, x2, a, b) -> (x1, x2, a, c) # Bifunctor ((,,,,) x1 x2 x3) # Methodsbimap :: (a -> b) -> (c -> d) -> (x1, x2, x3, a, c) -> (x1, x2, x3, b, d) #first :: (a -> b) -> (x1, x2, x3, a, c) -> (x1, x2, x3, b, c) #second :: (b -> c) -> (x1, x2, x3, a, b) -> (x1, x2, x3, a, c) # Bifunctor ((,,,,,) x1 x2 x3 x4) # Methodsbimap :: (a -> b) -> (c -> d) -> (x1, x2, x3, x4, a, c) -> (x1, x2, x3, x4, b, d) #first :: (a -> b) -> (x1, x2, x3, x4, a, c) -> (x1, x2, x3, x4, b, c) #second :: (b -> c) -> (x1, x2, x3, x4, a, b) -> (x1, x2, x3, x4, a, c) # Bifunctor ((,,,,,,) x1 x2 x3 x4 x5) # Methodsbimap :: (a -> b) -> (c -> d) -> (x1, x2, x3, x4, x5, a, c) -> (x1, x2, x3, x4, x5, b, d) #first :: (a -> b) -> (x1, x2, x3, x4, x5, a, c) -> (x1, x2, x3, x4, x5, b, c) #second :: (b -> c) -> (x1, x2, x3, x4, x5, a, b) -> (x1, x2, x3, x4, x5, a, c) #