[MLton] combining signatures

[Matthew Fluet]

On Sun, Jun 5, 2011 at 8:28 PM, Michael Norrish
<Michael.Norrish at nicta.com.au> wrote:
> is it possible to create a signature that merges One and Two without retyping all of the bindings?

Unfortunately, not in Standard ML without changing the signatures One and Two.

As Vesa mentioned (in the thread to which he pointed), the "Expressive
Language of Signatures" of Ramsey, Fisher, and Govereau
(http://mlton.org/References#RamseyFisherGovereau05) does provide ways
of slicing and dicing signatures to make such combinations easy.

OCaml recently (ver 3.12) added a "destructive" substitution
constraint for signatures to alleviate exactly this case
(http://caml.inria.fr/pub/distrib/ocaml-3.12/ocaml-3.12-refman.html#htoc111).