Shorthand for constructor function

Question

Is there any way to pass a constructor as a function?

type foo =
  | Foo of int
  | Bar of int

let foo x = Foo x
let bar = fun x -> Bar x

Is there any shorthand for the functions foo and bar? I want to pass a constructor as a function, but it seems unwieldy to write fun x -> Bar x.

Answer 1

camlspotter's answer was close enough, but in your case you want to use Variantslib and add with variants at the end of your type definition:

type foo = Foo of int | Bar of int with variants;;

gives you the following:

type foo = Foo of int | Bar of int
val bar : int -> foo = <fun>
val foo : int -> foo = <fun>                                                    
module Variants :
  sig
    val bar : (int -> foo) Variantslib.Variant.t
    val foo : (int -> foo) Variantslib.Variant.t
  end

Answer 2

Use Fieldslib: https://github.com/janestreet/fieldslib .

Adding with fields postfix at the type definition like:

type foo = | Foo of int | Bar of int with fields

and compile it with Fieldslib's syntax extension. It automatically generates foo and bar for you.

Answer 3

You can now use ppx_variants_conv, like this:

type 'a t =
  | A of 'a
  | B of char
  | C
  | D of int * int
  [@@deriving variants]