Hi,
Marc Battyani wrote: [Thanks for your feedback]
I was wondering (given zero e-mail traffic on this subject here) if somebody had noticed that Iterate outputs quite dubious type declarations
when being asked for them (i.e. (declare (iterate:declare-variables)))? I used it a few times. The (declare (iterate:declare-variables)). IIRC it worked for me.
I always tend to express myself too generally :-(
For *some* constructs, Iterate outputs wrong type declarations. It depends on a) the construct and b) the implementation (more precisely the results of TYPE-OF).
E.g. in CLISP, (type-of 0) -> BIT and (macroexpand-1'(iter:iter(declare(iter:declare-variables))(iter:repeat 0))) reveals (LET* ((#:COUNT3 0)) (DECLARE (TYPE BIT #:COUNT3)) ...) whose type is evidently broken.
Obviously the code was written with (type-of 0) -> FIXNUM in mind.
Widening that topic, I'm wondering whether generally, even the implementation's LOOP or other iteration constructs always produce correct declarations in border cases. E.g. suppose array-dimension-limit = most-positive-fixnum
Loop code traversing a vector could possibly be written like: (declare (fixnum running-var)) ; because array-dimension fits a fixnum (incf running-var step) ; might escape fixnum limit (when (> running-var limit) (loop-finish)) but not like this (let ((var (+ running-var step))) ; no type declaration for var, ; could be a bignum after last iteration (if (> var limit) (loop-finish)) (setq running-var var)) ; in this case var is not too large
Similarly, consider (dotimes (i most-positive-fixnum) (declare (fixnum i)) ...) Within the user-visible body, the type declaration holds. Yet dotimes could be implemented using (incf i) (when (> i #:limit) ...), thereby breaking the type declaration.
Is that just academic and I'm worrying too much?
Regards, Jörg Höhle.