Custom Query (1030 matches)

Sometimes, something like this happens.

Welcome to Clozure Common Lisp Version 1.2-r10446:10448M-trunk  (DarwinX8632)!
? (process-run-function "do nothing" (lambda ()))
#<PROCESS do nothing(2) [#<Unprintable IMMEDIATE : #xF3>] #x88CB886>

#xf3 is x8632::subtag-no-thread-local-binding.

One expect to see this:

#<PROCESS do nothing(2) [Reset] #x88CB886>

in the working-0711 branch, the compiler traps certain kinds of compile-time PROGRAM-ERRORs (at least), WARNs about them, and produces a function that, when executed, complains about whatever errors were detected at compile-time.

? (defun bogus (x y) (eq x) y) ; misplaced paren
;Compiler warnings :
;   In BOGUS: Required arguments in (EQ X) don't match lambda list (FORM1 FORM2).
BOGUS

Unfortunately, the function that's created in this case takes 0 arguments; unless it's called with 0 arguments, one won't see the compile-time error reported.

When this happens when something is defined interactively, any previous (more) correct version of the function is quietly replaced with the 0-arg error-signaling version. Under the old behavior (where an error was signaled at compile-time), the old (presumably working) definition would have remained in place. With the new behavior, it may be necessary to reload code (if possible) and repeat a number of development steps to get back to the point where one has the opportunity to correct a simple syntax error. (I noticed this while working on the compiler, and find this aspect of the new behavior to be a big impediment to productivity.)

If this happens during COMPILE-FILE, I assume that the same sort of unfortunate side-effects occur (unless one is lucky enough to press ^{C before the binary is loaded.)}

I think that I understand some of the motivations for this change and hope that we can think of ways of satisfying the needs of all concerned parties.

with-readtable-iterator is a macro proposed as a de-facto standard extension to Common Lisp by Tobias Rittweiler. It is currently implemented in the with-readtable-iterator branch of Git repository git://repo.or.cz/sbcl/tcr.git (​gitweb).

The macro allows efficient iteration over the reader macros provided in a particular readtable, more than can be provided with ANSI-standard functionality, especially given very large values of char-code-limit. Tobias's named-readtable (​Darcs) for SBCL and Clozure CL, which implements Allegro-like named readtables, uses with-readtable-iterator to merge macros provided by multiple readtables into a single readtable.

Attached is a patch made against r10880 that implements this macro and exports it from CCL. The `with-readtable-iterator' macro body itself is borrowed from Tobias's SBCL implementation.