API (preface.Preface_specs.Freer

type 'a f

The parametric type (which, unlike a Preface_specs.Free_monad don't need to be a Preface_specs.Functor).

type _ t =

| Return : 'a -> 'a t
| Bind : 'b f * ('b -> 'a t) -> 'a t

The type held by Freer monad.

type ('a, 'b) handle = ('a -> 'b) -> 'a f -> 'b

type 'a handler = {

handler : 'b. ('b, 'a) handle;

}

The handler type. Which is a Natural transformation from the Freer Monad to an unwrapped Identity monad.

val perform : 'a f -> 'a t

Create a new 'a t from a 'a f.

val run : 'a handler -> 'a t -> 'a

Execute a given handler for given data

module To_monad
  (Monad : Monad.CORE) : 
  TO_MONAD
    with type 'a t := 'a t
     and type 'a f := 'a f
     and type 'a monad := 'a Monad.t

Functor API

A Freer monad is also an Preface_specs.Functor.

module Functor : Functor.API with type 'a t = 'a t

Applicative API

A Freer monad is also an Preface_specs.Applicative.

module Applicative : Applicative.API with type 'a t = 'a t

Selective API

A Freer monad is also an Preface_specs.Selective.

module Selective : Selective.API with type 'a t = 'a t

Monad API

A Freer monad is also (obviously) a Preface_specs.Monad.

module Monad : Monad.API with type 'a t = 'a t

Type

Functions

include Indexed_monad.WITH_RETURN with type ('a, 'index) t := 'a t

include Indexed_bind.WITH_BIND with type ('a, 'index) t := 'a t

val bind : ('a -> 'b t) -> 'a t -> 'b t

bind f m passes the result of computation m to function f.

include Indexed_monad.WITH_RETURN with type ('a, 'index) t := 'a t

include Indexed_bind.WITH_MAP_AND_JOIN with type ('a, 'index) t := 'a t

val map : ('a -> 'b) -> 'a t -> 'b t

Mapping over from 'a to 'b.

val join : 'a t t -> 'a t

join remove one level of monadic structure, projecting its bound argument into the outer level.

include Indexed_monad.WITH_RETURN with type ('a, 'index) t := 'a t

val return : 'a -> 'a t

Lift a value into a t.

include Indexed_bind.WITH_KLEISLI_COMPOSITION with type ('a, 'index) t := 'a t

val compose_left_to_right : ('a -> 'b t) -> ('b -> 'c t) -> 'a -> 'c t

Composing monadic functions using Kleisli Arrow (from left to right).

val compose_right_to_left : ('b -> 'c t) -> ('a -> 'b t) -> 'a -> 'c t

Composing monadic functions using Kleisli Arrow (from right to left).

val lift : ('a -> 'b) -> 'a t -> 'b t

Mapping over t from 'a to 'b.

val lift2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t

Lift a binary function that acts on arbitrary values into a function that acts t values.

val lift3 : ('a -> 'b -> 'c -> 'd) -> 'a t -> 'b t -> 'c t -> 'd t

Lift a ternary function that acts on arbitrary values into a function that acts t values.

val replace : 'a -> 'b t -> 'a t

Create a new t, replacing all values of the given functor by given a value of 'a.

val void : 'a t -> unit t

Create a new t, replacing all values in the given functor by unit.

Infix operators

module Infix : Indexed_monad.INFIX with type ('a, 'index) t := 'a t

val (=|<) : ('a -> 'b) -> 'a t -> 'b t

Infix version of CORE.map.

val (>|=) : 'a t -> ('a -> 'b) -> 'b t

Infix flipped version of CORE.map.

val (>>=) : 'a t -> ('a -> 'b t) -> 'b t

Infix flipped version of CORE.bind.

val (=<<) : ('a -> 'b t) -> 'a t -> 'b t

Infix version of CORE.bind.

val (>=>) : ('a -> 'b t) -> ('b -> 'c t) -> 'a -> 'c t

Infix version of CORE.compose_left_to_right.

val (<=<) : ('b -> 'c t) -> ('a -> 'b t) -> 'a -> 'c t

Infix version of OPERATION.compose_right_to_left.

val (>>) : unit t -> 'b t -> 'b t

Sequentially compose two actions, discarding any value produced by the first.

val (<<) : 'a t -> unit t -> 'a t

Sequentially compose two actions, discarding any value produced by the second.

val (<$>) : ('a -> 'b) -> 'a t -> 'b t

Infix version of CORE.map.

val (<&>) : 'a t -> ('a -> 'b) -> 'b t

Flipped and infix version of CORE.map.

val (<$) : 'a -> 'b t -> 'a t

Infix version of OPERATION.replace.

val ($>) : 'a t -> 'b -> 'b t

Flipped and infix version of OPERATION.replace.

Syntax

module Syntax : Indexed_monad.SYNTAX with type ('a, 'index) t := 'a t

val let* : 'a t -> ('a -> 'b t) -> 'b t

Syntactic shortcuts for flipped version of CORE.bind:

let* x = e in f is equals to bind (fun x -> f) e.

val let+ : 'a t -> ('a -> 'b) -> 'b t

let operator for mapping.