Either (preface.Preface

Either.t is the simplest sum type. In addition to allowing the generic description of sum types, it allows the description of a disjunction, for example to generalise a conditional branching.

Type

type ('a, 'b) t = ('a, 'b) Stdlib.Either.t =

| Left of 'a
| Right of 'b

Implementation

The set of concrete implementations for Either.t.

Bifunctor

module Bifunctor : Preface_specs.BIFUNCTOR with type ('a, 'b) t = ('a, 'b) t

Delayed implementation

By setting the left type of Either.t it is possible to get implementations for abstractions on constructors of type with an arity of 1.

Functor

module Functor
  (T : Preface_specs.Types.T0) : 
  Preface_specs.FUNCTOR with type 'a t = (T.t, 'a) Bifunctor.t

Alt

module Alt
  (T : Preface_specs.Types.T0) : 
  Preface_specs.ALT with type 'a t = (T.t, 'a) Bifunctor.t

Applicative

Either.t implements Preface_specs.APPLICATIVE and introduces an interface to define Preface_specs.TRAVERSABLE using Either as an iterable structure.

module Applicative
  (T : Preface_specs.Types.T0) : 
  Preface_specs.Traversable.API_OVER_APPLICATIVE
    with type 'a t = (T.t, 'a) Bifunctor.t

Selective

module Selective
  (T : Preface_specs.Types.T0) : 
  Preface_specs.SELECTIVE with type 'a t = (T.t, 'a) Bifunctor.t

Monad

Either.t implements Preface_specs.MONAD and introduces an interface to define Preface_specs.TRAVERSABLE using Either as an iterable structure.

module Monad
  (T : Preface_specs.Types.T0) : 
  Preface_specs.Traversable.API_OVER_MONAD
    with type 'a t = (T.t, 'a) Bifunctor.t

Invariant Functor

module Invariant
  (T : Preface_specs.Types.T0) : 
  Preface_specs.INVARIANT with type 'a t = (T.t, 'a) Bifunctor.t

Foldable

module Foldable
  (T : Preface_specs.Types.T0) : 
  Preface_specs.FOLDABLE with type 'a t = (T.t, 'a) Bifunctor.t

Additional functions

Additional functions to facilitate practical work with Either.t.

val pure : 'b -> ('a, 'b) t

Create a value from 'b to ('a, 'b) t, a value wrapped in Right.

val equal : 
  ('a -> 'a -> bool) ->
  ('b -> 'b -> bool) ->
  ('a, 'b) t ->
  ('a, 'b) t ->
  bool

Equality between Either.t.

val pp : 
  (Stdlib.Format.formatter -> 'a -> unit) ->
  (Stdlib.Format.formatter -> 'b -> unit) ->
  Stdlib.Format.formatter ->
  ('a, 'b) t ->
  unit

Formatter for pretty-printing for Either.t.