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
or
type 'a t
include Invariant.S1 with type 'a t := 'a t
module type S = Base__.Invariant_intf.S
module type S1 = Base__.Invariant_intf.S1
module type S2 = Base__.Invariant_intf.S2
module type S3 = Base__.Invariant_intf.S3
val invariant : Base__.Source_code_position0.t ‑> 'a ‑> ('a ‑> Sexp.t) ‑> (unit ‑> unit) ‑> unit
invariant here 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 [%here] t [%sexp_of: t] (fun () ->
... check t's invariants ... )
For polymorphic types:
let invariant check_a t =
Invariant.invariant [%here] t [%sexp_of: _ t] (fun () -> ... )
It's okay to use [%sexp_of: _ t]
because the exceptions raised by check_a
will
show the parts that are sexp_opaque at top-level.
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;
}
[@@deriving_inline fields][@@@end]
let invariant t : unit =
Invariant.invariant [%here] t [%sexp_of: t] (fun () ->
let check f = Invariant.check_field t f in
Fields.iter
~foo:(check Foo.invariant)
~bar:(check Bar.invariant))
;;