Noel Welsh wrote at 09/02/2010 04:49 AM:
GHC allows user specified rewrite rules:
http://www.haskell.org/ghc/docs/6.12.2/html/users_guide/rewrite-rules.html
I don't know how effective they are in practice.
Neat. But I'd be fine with just a hook procedure being called with with
just the version identifier and whatever intermediate representation the
compiler happens to have in that version (say, a macro-expanded syntax
tree with reference annotations). Beyond that point, the IR is simply
undocumented internals that can be poked around, with no special
transformation language required. An optimization programmer can apply
whatever pattern-matching or whatnot they want to help with the
transformation/manipulation.
Independently, a third-party PLaneT package author could try to provide
a higher-level library for use by hook optimization programmers, that
abstracts across different versions of a Racket hook phase IR. Perhaps
it would look much like these GHC rewrite rules, "syntax-case", or one
of the various Scheme pattern-matching and logic-programming libraries.
I am currently thinking of these pluggable optimizations as potentially
unsafe indulgences for high-performance computing and research
prototyping. However, I have a greater interest in this not
significantly impeding the other evolution of Racket (by, e.g.,
distracting Matthew or making compiler improvements more difficult).
But if anyone who does the work has other priorities or other ideas,
that's good.
--
http://www.neilvandyke.org/
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