Module Invariant_intf

module Invariant_intf: sig .. end

This module defines signatures that are to be included in other signatures to ensure a consistent interface to invariant-style functions. There is a signature (S, S1, S2, S3) for each arity of type. Usage looks like:

      type t
      include Invariant.S with type t := t

      type 'a t
      include Invariant.S1 with type 'a t := 'a t

val __pa_ounit_275876e34cf609db118f3d84b799a790 : string

      type t
      include Invariant.S with type t := t

      type 'a t
      include Invariant.S1 with type 'a t := 'a t

type 'a t = 'a -> unit

type 'a inv = 'a t

module type S = sig .. end

module type S1 = sig .. end

module type S2 = sig .. end

module type S3 = sig .. end

module type Invariant = sig .. end

      type t
      include Invariant.S with type t := t

      type 'a t
      include Invariant.S1 with type 'a t := 'a t

invariant name t sexp_of_t f runs f (), and if f raises, wraps the exception in an Error.t that states "invariant failed" and includes both the exception raised by f, as well as sexp_of_t t. Idiomatic usage looks like:

        invariant "Foo.invariant" t <:sexp_of< t >> (fun () ->
          ... check t's invariants ... )

check_field is used when checking invariants using Fields.iter. It wraps an exception raised when checking a field with the field's name. Idiomatic usage looks like:

        type t =
          { foo : Foo.t;
            bar : Bar.t;
          }
        with fields

        let invariant t : unit =
          invariant "Foo.invariant" t <:sexp_of< t >> (fun () ->
            let check f = Invariant.check_field t f in
            Fields.iter
              ~foo:(check Foo.invariant)
              ~bar:(check Bar.invariant))
        ;;