Module `Base.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)

module type Infix = Base__.Comparable_intf.Infix

module type S = Base__.Comparable_intf.S

module type Polymorphic_compare = Base__.Comparable_intf.Polymorphic_compare

module type Validate = Base__.Comparable_intf.Validate

module type With_zero = Base__.Comparable_intf.With_zero

val lexicographic : ('a -> 'a -> int) list -> 'a -> 'a -> int: lexicographic cmps x y compares x and y lexicographically using functions in the list cmps.

val lift : ('a -> 'a -> 'result) -> f:('b -> 'a) -> 'b -> 'b -> 'result: lift cmp ~f x y compares x and y by comparing f x and f y via cmp.

val reverse : ('a -> 'a -> 'result) -> 'a -> 'a -> 'result

reverse cmp x y = cmp y x

Reverses the direction of asymmetric relations by swapping their arguments. Useful, e.g., for relations implementing "is a subset of" or "is a descendant of".

Where reversed relations are already provided, use them directly. For example, Comparable.S provides ascending and descending, which are more readable as a pair than compare and reverse compare. Similarly, <= is more idiomatic than reverse (>=).

val equal : ('a -> 'a -> int) -> 'a -> 'a -> bool
val max : ('a -> 'a -> int) -> 'a -> 'a -> 'a
val min : ('a -> 'a -> int) -> 'a -> 'a -> 'a

module Inherit : functor (C : sig ... end) -> functor (T : sig ... end) -> S with type t := T.t: Inherit comparability from a component.

module Make : functor (T : sig ... end) -> S with type t := T.t

module Make_using_comparator : functor (T : sig ... end) -> S with type t := T.t with type comparator_witness := T.comparator_witness

module Poly : functor (T : sig ... end) -> S with type t := T.t

module Validate : functor (T : sig ... end) -> Validate with type t := T.t

module With_zero : functor (T : sig ... end) -> With_zero with type t := T.t

module Validate_with_zero : functor (T : sig ... end) -> sig ... end