package preface

  1. Overview
  2. Docs
package preface
Legend:
Page
Library
Module
Module type
Parameter
Class
Class type
Source

Source file freer_monad.ml

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
open Preface_core.Fun.Infix

module Over (Type : Preface_specs.Types.T1) = struct
  type 'a f = 'a Type.t

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

  let perform f = Bind (f, fun a -> Return a)

  type ('a, 'b) handle = ('a -> 'b) -> 'a f -> 'b
  type 'a handler = { handler : 'b. ('b, 'a) handle }

  module To_monad (Monad : Preface_specs.Monad.CORE) = struct
    type ('a, 'b) handle = ('a -> 'b Monad.t) -> 'a f -> 'b Monad.t
    type 'a handler = { handler : 'b. ('b, 'a) handle }

    let run f =
      let rec loop_run = function
        | Return a -> Monad.return a
        | Bind (intermediate, continue) ->
          let k x = loop_run (continue x) in
          f.handler k intermediate
      in
      loop_run
    ;;
  end

  let run f =
    let rec loop_run = function
      | Return a -> a
      | Bind (intermediate, continue) ->
        let k x = loop_run (continue x) in
        f.handler k intermediate
    in
    loop_run
  ;;

  let rec map f = function
    | Return x -> Return (f x)
    | Bind (i, c) -> Bind (i, c %> map f)
  ;;

  module Functor = Functor.Via_map (struct
    type nonrec 'a t = 'a t

    let map = map
  end)

  module Applicative = Applicative.Via_pure_and_apply (struct
    type nonrec 'a t = 'a t

    let pure a = Return a

    let rec apply f a =
      match f with
      | Return f' -> map f' a
      | Bind (i, c) -> Bind (i, c %> fun f -> apply f a)
    ;;
  end)

  module Monad = Monad.Via_return_and_bind (struct
    type nonrec 'a t = 'a t

    let return a = Return a

    let rec bind f = function
      | Return a -> f a
      | Bind (i, c) -> Bind (i, c %> bind f)
    ;;
  end)

  module Selective =
    Selective.Over_applicative_via_select
      (Applicative)
      (Selective.Select_from_monad (Monad))

  include (Monad : Preface_specs.MONAD with type 'a t := 'a t)
end
OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct