Re: Enable truncation of exception output

[Andy Wingo]

Hi :)

On Fri 10 Mar 2017 10:07, address@hidden (Ludovic Courtès) writes:

> I’d be in favor of something more conservative, notably because
> ‘simple-format’ remains faster than ‘format’:

Ah indeed.  simple-format does appear to be much faster.

Tested using:

  (define-syntax-rule (do-times count exp) (let lp ((n 0)) (when (< n count) 
exp (lp (1+ n)))))
  ,time (string-length (call-with-output-string (lambda (p) (do-times #e1e4 
(format p "foo")))))

and for simple-format too, and when adding a ~a.

Clearly the answer here is to work on improving the performance of
"format" :)

>   1. Remove ‘set!’ in (ice-9 format), which has always been a bad idea.

This is *not* conservative.  We would certainly break users' code with
this.  I know there's -Wformat but still :)

>   2. For exception printers, use some autoload magic, just like we do
>      for the debugger.

This is hard for boot reasons -- you might get an exception before you
are able to load modules.  Of course this doesn't happen in the normal
case but it would make Guile hacking a bit harder.  Still, perhaps it is
possible.

Andy