[flexi-streams-devel] New release 0.9.0

[Attila Lendvai]

> > Instead of creating a class for each external format in order to
> > optimize STREAM-READ-CHAR, we can just take all decision making code
> > out from STREAM-READ-CHAR to (SETF FLEXI-STREAM-EXTERNAL-FORMAT).
>
> Yes, I initially wrote something like that, but I thought it was kind
> of ugly and hard to maintain.  Anyway, the issues with SBCL are gone

<rant>

a partial evaluation framework is badly missing here. oh well, even
(the practical) common lisp is missing this and that... :)

we experimented with similar problems using hacks like backquote
stripping to have a "compiler" besides the function itself. basically
generate an additional macro in a defun* which is hand annotated by
backquote and comma-eval's. backquoting is stripped down in the defun
version, and kept in the defmacro. with the help of a code-walker,
replace calls to these defun*'s to the macro variants. it is
implementation dependent, supports only a single configuration of PE,
but keeps the code mostly readable and works fine in simple situations
like this. traces of the hackery available (temporarily?) at:
http://common-lisp.net/cgi-bin/darcsweb/darcsweb.cgi?r=cl-wdim-pmpe;a=summary
(pmpe stands for poor man's partial evaluator... :)

then we tried lambda's that capure and funcall other lambda's (the
solution proposed in Anton's mail). works with stock cl, but the code
needs to be uglyfied and inlining is not possible which can be a big
loss in certain situations.

and then we also tried heavy (declaim (inline ...)) annotations on
sbcl and call 'compile at runtime with constant inputs to the topmost
functions, but no compiler will use invariants like "this slot in this
object will not change the entire time this lambda will be used", so
this has limited flexibility.

to make sure specialized lambda's are properly recompiled when needed,
we used computed-class.

but all in all, implementations are missing a way to hand-annotate
dataflow-like constraints that the compiler could use to partially
evaluate certain pieces of the code and recompile when a dependency is
changed. (automatic discovery of this (as opposed to hand annonation)
is sci-fi currently. well, for me at least... :)

</rant>

-- 
- attila

"- The truth is that I've been too considerate, and so became
unintentionally cruel...
 - I understand.
 - No, you don't understand! We don't speak the same language!"
(Ingmar Bergman - Smultronstället)