Module Core_kernel.Comparable
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)
end
Then 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 = ..
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 = Core_kernel__.Comparable_intf.Infix
module type S_plain = Core_kernel__.Comparable_intf.S_plain
module type S = Core_kernel__.Comparable_intf.S
module type S_binable = Core_kernel__.Comparable_intf.S_binable
module type S_common = Core_kernel__.Comparable_intf.S_common
module type Validate = Core_kernel__.Comparable_intf.Validate
module type With_zero = Core_kernel__.Comparable_intf.With_zero
val lexicographic : ('a -> 'a -> int) list -> 'a -> 'a -> int
lexicographic cmps x y
comparesx
andy
lexicographically using functions in the listcmps
.
val lift : ('a -> 'a -> 'int_or_bool) -> f:('b -> 'a) -> 'b -> 'b -> 'int_or_bool
lift cmp ~f x y
comparesx
andy
by comparingf x
andf y
viacmp
.
val reverse : ('a -> 'a -> 'int_or_bool) -> 'a -> 'a -> 'int_or_bool
reverse cmp x y = cmp y x
Note: The
Comparable.S
interface exports bothascending
anddescending
comparisons, so in most cases, it's better to use those.
module Inherit : functor (C : sig ... end) -> functor (T : sig ... end) -> S with type t := T.t
Inherit comparability from a component.
Comparison-only Functors
These functors require only type t
and val compare
. They do not require val
sexp_of_t
, and do not generate container datatypes.
module Polymorphic_compare : functor (T : sig ... end) -> Polymorphic_compare with type t := T.t
Make Functors
The Comparable Make functor family allows users to choose among the following attributes:
*_using_comparator
or not*_binable
or not*_plain
or not
Thus 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.t
module Make_plain_using_comparator : functor (T : sig ... end) -> S_plain with type t := T.t with type comparator_witness := T.comparator_witness
module Make_using_comparator : functor (T : sig ... end) -> S with type t := T.t with type comparator_witness := T.comparator_witness
module Make_binable : functor (T : sig ... end) -> S_binable with type t := T.t
module Make_binable_using_comparator : functor (T : sig ... end) -> S_binable with type t := T.t with type comparator_witness := T.comparator_witness
module Extend : functor (M : Base.Comparable.S) -> functor (X : sig ... end) -> S with type t := M.t with type comparator_witness := M.comparator_witness
module Extend_binable : functor (M : Base.Comparable.S) -> functor (X : sig ... end) -> S_binable with type t := M.t with type comparator_witness := M.comparator_witness
module Map_and_set_binable : functor (T : sig ... end) -> Map_and_set_binable with type t := T.t
module 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_witness
module Validate_with_zero : functor (T : sig ... end) -> sig ... end
module Stable : sig ... end