RE: [Caml-list] Operator for Lazy.force?

[David Allsopp <dra-news@metastack.com>]

Damien Doligez wrote:
> On 2013-10-30, at 22:33, Dmitry Grebeniuk wrote:
> 
> >  So theirs ( !! ) operator will override Pervasives' one.
> > What's the problem?  Anyway projects you've mentioned don't use Lazy,
> > so there's no chance of "operator clash".
> 
> It cannot be in Pervasives, since that would introduce a circular
> dependency with Lazy. It doesn't belong in Pervasives anyway.

Out of belligerent curiosity only, is that definitely true? lazy.mli doesn't create an opaque type for 'a Lazy.t so wouldn't

external ( !! ) : 'a lazy_t -> 'a = "%lazy_force"

in pervasives.ml/mli work out of the box and to all intents and purposes have the right effect?

Even if you wanted to have the neater type 'a Lazy.t -> 'a, lazy.ml only refers to a handful of trivial externals and constants in obj.ml and only requires ( <> ) and ( || ) from Pervasives. Isn't it the case that as Pervasives would then only refer to a *type* in Lazy that you wouldn't have the (presumably unwanted) side-effect of even "Hello World" being linked with Lazy?

So either with some very minor internal code duplication (or a bit of pre-processing), is there anything else which means that you couldn't add that declaration to Pervasives without the circular dependency?

I agree that it probably doesn't belong there (although I can see the other side, given that the lazy keyword is, um, "pervasive") - just curious as to if it's possible :o)


David