Re: srfi-18 and the vm

[Ludovic Courtès]

Hello!

Andy Wingo <address@hidden> writes:

> On Sat 23 May 2009 11:52, Neil Jerram <address@hidden> writes:
>
>> Andy Wingo <address@hidden> writes:
>>
>>> With psyntax running a pre-analysis phase on all source code, we can do
>>> away with lazy memoization entirely -- a neat hack, but it made eval.c
>>> buggy and impenetrable. I'll write more about that in the future.
>>
>> Anticipating your "more in the future", do you mean that the
>> pre-analysis does all the memoization in advance?
>
> It does not now, but it could.
[...]

> In compile mode, these procedures create tree-il objects. In eval mode,
> they create s-expressions, so that the expander can work before modules
> are booted. (The mode is the second parameter to sc-expand; it's eval
> mode by default, but the compiler sets it to compile mode.)
>
> One should be able to memoize ilocs in from the result of the output, in
> a second pass, given that there are so few forms. Of course some
> memoization can happen lazily too, e.g. global lookup;
[...]

I'm slightly concerned that doing things ahead of time rather than just
in time (i.e., lazily) would have a negative impact on the interpreter's
start-up time, which may be noticeable for short-lived scripts.

What do you think?

Thanks,
Ludo'.