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Independent optimizing compilation [was: fundamental design issues]

bear <bear@xxxxxxxxx> writes:

> In C in particular, this turned out to facilitate a
> very useful pattern.  A "header file" with nothing but
> forward declarations allows most interdependency problems
> to be solved statically

You're kidding, right?  (Unless you mean "most" = >50%.) :-)

But anyway, your concern is a very valid one.  Here's what I think we
came down on:

- The current proposal doesn't preclude a future extension for
  optionally specifying more static information about the names being
  exported, as is possible, for instance, in Scheme 48 or Bigloo.

- Any such extension is bound to provide only incomplete static
  information about the thing being exported, and thus preclude
  certain kinds of optimization.

- A type language (or flow language or whatever) would be a topic for
  active research, which I don't think we were prepared to do.

- Consequently, highly optimizing compilers (like Chez Scheme, for
  example) really need to look at the entire source code of the
  everything you're importing (or some representation thereof) to do a
  good job.

- Macros require you to have some representation of the source code of
  the library you're importing anyway.  (Some people might argue this
  is a design mistake in the library syntax---several people are
  working on macro/module systems that don't have this property.  But
  once again, (very) active ongoing research, not ready for R6RS.)

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla