Comparable extends Base.Comparable and provides functions for
comparing like types.
Usage example:
module Foo = struct
module T = struct
type t = ... [@@deriving compare, sexp]
end
include T
include Comparable.Make (T)
endThen include Comparable.S in the signature (see Comparable_intf for an
example).
To add an Infix submodule:
module C = Comparable.Make (T)
include C
module Infix = (C : Comparable.Infix with type t := t)Common pattern: 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 = ..
endOpening Date would shadow now, but opening Date.O doesn't:
let now = .. in
let someday = .. in
Date.O.(now > someday)module type Infix = Core_kernel__.Comparable_intf.Infixmodule type S_plain = Core_kernel__.Comparable_intf.S_plainmodule type S = Core_kernel__.Comparable_intf.Smodule type S_binable = Core_kernel__.Comparable_intf.S_binablemodule type S_common = Core_kernel__.Comparable_intf.S_commonmodule type Validate = Core_kernel__.Comparable_intf.Validatemodule type With_zero = Core_kernel__.Comparable_intf.With_zeroval lexicographic : ('a ‑> 'a ‑> int) list ‑> 'a ‑> 'a ‑> intlexicographic cmps x y compares x and y lexicographically using functions in the
list cmps.
val lift : ('a ‑> 'a ‑> 'int_or_bool) ‑> f:('b ‑> 'a) ‑> 'b ‑> 'b ‑> 'int_or_boollift cmp ~f x y compares x and y by comparing f x and f y via cmp.
The Comparable Make functor family allows users to choose among the following attributes:
*_using_comparator or not*_binable or not*_plain or notThus there are functors like Make_plain or Make_binable_using_comparator, etc.
module Make_plain : functor (T : sig ... end) -> S_plain with type t := T.tmodule Make_plain_using_comparator : functor (T : sig ... end) -> S_plain with type t := T.t with type comparator_witness := T.comparator_witnessmodule Make_using_comparator : functor (T : sig ... end) -> S with type t := T.t with type comparator_witness := T.comparator_witnessmodule Make_binable : functor (T : sig ... end) -> S_binable with type t := T.tmodule Make_binable_using_comparator : functor (T : sig ... end) -> S_binable with type t := T.t with type comparator_witness := T.comparator_witnessmodule Extend : functor (M : Base.Comparable.S) -> functor (X : sig ... end) -> S with type t := M.t with type comparator_witness := M.comparator_witnessmodule Extend_binable : functor (M : Base.Comparable.S) -> functor (X : sig ... end) -> S_binable with type t := M.t with type comparator_witness := M.comparator_witnessmodule Map_and_set_binable : functor (T : sig ... end) -> Map_and_set_binable with type t := T.tmodule Map_and_set_binable_using_comparator : functor (T : sig ... end) -> Map_and_set_binable with type t := T.t with type comparator_witness := T.comparator_witnessmodule Validate_with_zero : functor (T : sig ... end) -> sig ... endThe following module types and functors may be used to define stable modules:
module Stable : sig ... end