[Caml-list] Infer least upper bound for arguments to functions in rows

["Christoph Höger" <christoph.hoeger@tu-berlin.de>]

Dear experts,

is there a way to infer a compatible type for the argument to t#x in the
function:

let a t = ignore (t#x t) ; t#x (object end) ;;

I can easily provide a compatible t, e.g.:

let t = object method x _ = 23 end

I can also use a coercion:

let a t = ignore (t#x (t :> < >)) ; t#x (object end) ;;

Since < > is the common supertype of both arguments.

My problem is that in general < > won't suffice for the common type, and
finding it is a rather complicated process. So I wonder if there is some
clever rewriting of the function that makes ocamlc infer that type for me?

Is there any expression that for two (expressions with) different input
types yields (an expression of) the largest common supertype?

regards,

Christoph
-- 
Christoph Höger

Technische Universität Berlin
Fakultät IV - Elektrotechnik und Informatik
Übersetzerbau und Programmiersprachen

Sekr. TEL12-2, Ernst-Reuter-Platz 7, 10587 Berlin

Tel.: +49 (30) 314-24890
E-Mail: christoph.hoeger@tu-berlin.de