Registering OCaml values with the C runtime.
This module allows OCaml values to be registered with the C runtime under a symbolic name, so that C code can later call back registered OCaml functions, or raise registered OCaml exceptions.
val register : string -> 'a -> unitCallback.register n v registers the value v under
the name n. C code can later retrieve a handle to v
by calling caml_named_value(n).
val register_exception : string -> exn -> unitCallback.register_exception n exn registers the
exception contained in the exception value exn
under the name n. C code can later retrieve a handle to
the exception by calling caml_named_value(n). The exception
value thus obtained is suitable for passing as first argument
to raise_constant or raise_with_arg.