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Defines functors for making modules comparable.
Usage example:
module Foo = struct
module T = struct
type t = ... [@@deriving_inline compare, sexp
@@@end] end include T include Comparable.Make (T) end
Then include Comparable.S in the signature
module Foo : sig
type t = ...
include Comparable.S with type t := t
end
To add an Infix submodule:
module C = Comparable.Make (T)
include C
module Infix = (C : Comparable.Infix with type t := t)
A common pattern is to define a module O with a restricted signature. It aims to be (locally) opened to bring useful operators into scope without shadowing unexpected variable names. E.g., in the Date module:
module O = struct
include (C : Comparable.Infix with type t := t)
let to_string t = ..
end
Opening Date would shadow now, but opening Date.O doesn't:
let now = .. in
let someday = .. in
Date.O.(now > someday)