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open Preface_core.Fun
include Preface_core.Shims.Either
let pure x = Right x
module Bifunctor = Preface_make.Bifunctor.Via_bimap (struct
type nonrec ('a, 'b) t = ('a, 'b) t
let bimap f g = function Left x -> Left (f x) | Right x -> Right (g x)
end)
module Functor (T : Preface_specs.Types.T0) =
Preface_make.Functor.Via_map (struct
type nonrec 'a t = (T.t, 'a) t
let map f x = Bifunctor.bimap id f x
end)
let traverse_aux pure map f = function
| Left x -> pure (Left x)
| Right x -> map right (f x)
;;
module Alt (T : Preface_specs.Types.T0) =
Preface_make.Alt.Over_functor
(Functor
(T))
(struct
type nonrec 'a t = (T.t, 'a) t
let combine x y = (match (x, y) with (Left _, a) -> a | (a, _) -> a)
end)
module Applicative (T : Preface_specs.Types.T0) = struct
module A = Preface_make.Applicative.Via_apply (struct
module F = Functor (T)
type nonrec 'a t = (T.t, 'a) t
let pure = pure
let apply fa xa =
(match (fa, xa) with (Right f, x) -> F.map f x | (Left x, _) -> Left x)
;;
end)
module T (A : Preface_specs.APPLICATIVE) =
Preface_make.Traversable.Over_applicative
(A)
(struct
type 'a t = 'a A.t
type 'a iter = (T.t, 'a) Bifunctor.t
let traverse f x = traverse_aux A.pure A.map f x
end)
include Preface_make.Traversable.Join_with_applicative (A) (T)
end
module Monad (T : Preface_specs.Types.T0) = struct
module M = Preface_make.Monad.Via_bind (struct
type nonrec 'a t = (T.t, 'a) t
let return = pure
let bind f = function Right x -> f x | Left x -> Left x
end)
module T (M : Preface_specs.MONAD) =
Preface_make.Traversable.Over_monad
(M)
(struct
type 'a t = 'a M.t
type 'a iter = (T.t, 'a) Bifunctor.t
let traverse f x = traverse_aux M.return M.map f x
end)
include Preface_make.Traversable.Join_with_monad (M) (T)
end
module Foldable (T : Preface_specs.Types.T0) =
Preface_make.Foldable.Via_fold_right (struct
type nonrec 'a t = (T.t, 'a) t
let fold_right f x acc = (match x with Left _ -> acc | Right v -> f v acc)
end)
let equal f g left right =
match (left, right) with
| (Left x, Left y) -> f x y
| (Right x, Right y) -> g x y
| _ -> false
;;
let pp f g formater = function
| Left x -> Format.fprintf formater "Left (%a)" f x
| Right x -> Format.fprintf formater "Right (%a)" g x
;;