meow/meow.data/Functor

Functor

trait Functor[F[_]]

A type F is a Functor if it provides a function fmap which, given any types A and B lets you apply any function from ~A => B~ to turn an F[A] into an F[B], preserving the structure of F. Furthermore F needs to adhere to the following:

Identity

fa <#> identity == identity(fa)



Composition


(f compose g) `<$>` fa  == (map[F](f) compose map[F](g))(fa)



Companion
object
class Object
trait Matchable
class Any
Value members
Abstract methods
 def fmap[A, B](f: A => B): F[A] => F[B]
Extensions
Extensions
extension (fa: F[A])
@targetName("voidLeft") 
 def $>[A, B](a: B): F[B]
Drop whatever value A on left and return F[B] on the right


Drop whatever value A on left and return F[B] on the right


Example
Option(1) `$>` 3 == Option(3)



@targetName("mapFlipped") 
 def <#>[A, B](f: A => B): F[B]
Usually fmap takes function first, mapFlipped takes data first


Usually fmap takes function first, mapFlipped takes data first


Example
fa <#> identity == identity(fa)



 def map[A, B](f: A => B): F[B]
 def void[A, B]: F[Unit]
Void F[A] and return F[Unit]


Void F[A] and return F[Unit]


Example
Option(2).void == Option(())