On Jan 29, 2014, at 7:41 AM, Frank Shearar <frank.shearar at gmail.com> wrote:

> On 29 January 2014 14:16, Robert Withers <robert.w.withers at gmail.com> wrote:
> 
>> The other reason is that I wanted the returned promise to be typed as the real return and let the inferencer do its thing and rewrite send sites from dynamic lookup to direct calls.  I was told that Hindley-Milner was what I wanted.  *shrug*
> 
> Um, that sounds a bit weird, to be honest. A promise surely _can't_ be
> typed as the real return since there _is_ no real return: a promise
> can break! In Scala-ish terms (I've not written any Scala for about
> two years...), a Promise[Int] is fundamentally different to an Int
> because the latter is just a value whereas the former may or may not
> result at some point in a value. It's only once a Promise has resolved
> that things get interesting. And it sounds here like this is when
> you'd like to optimise the Promise wrapper away, right?

I was under the impression that Hindley-Milner was able to construct union types, which is why it was recommended to me.

> 
>> The strategy behind my request is to see if Cog could support multiple languages and modern languages - i.e. broadly used languages.  It seems a dynamic runtime is better than a static vm to support both flavors of languages, though runtime feedback type inferencing seems important, in my gut.  Maybe it is just cool tech, great for ops.
> 
> Cog _does_ support multiple languages: Squeak and Newspeak. Given that
> Ruby can run on top of Gemstone (Maglev), there shouldn't be an issue
> with running other languages on top of Cog... assuming there's someone
> sufficiently interested/available to actually _do_ that. (Oh, and of
> course IBM ran Java on top of a Smalltalk VM in Visual Age for Java.)

It may be clearer for me to say that it would be awfully nice if Cog allowed for bytecode virtualization.  In 64-bit values, a couple of bits for bytecode index (have a cache of 4 bytecode sets, so 4 different languages, concurrently executing).  Add a bit for a capability/promise for pipelining.  All at the expense of the range of the immediates, but maybe that’s ok, I do not know.


- Robert

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