I seem to recall proposing such a scheme, yes, However, the initiative, such as it was, has rather been side-lined by the, perhaps belated, realisation that I'm going to have to high-jack your thread WeiDU is in a rather vulnerable state, technologically. Already WeiDU cannot be compiled with contemporary OCaml and who knows how long it will be until it is no longer straightforward to build old-enough versions of OCaml on contemporary operating systems.
I have slowly come to the realisation that a re-implementation will be necessary, as it would be a very extensive re-write to address the mutable strings, anyway, and if I'm doing major work like that I'd better choose a language that has parallelism. I have begun sketching on a project like that, but it might surprise you to learn I have nothing to show for it, yet.