Re: Trying to understand trace limit

[Dave Musicant via General Guile related discussions <guile-user@gnu.org>]

I'm using Guile 2.2.7, under Ubuntu 20.04.


--
Dave

On 10/3/20 2:15 AM, Aleix Conchillo Flaqué wrote:
>
> Hi Dave,
>
> On Mon, Sep 28, 2020 at 10:06 AM Dave Musicant <dmusicant@carleton.edu 
> <mailto:dmusicant@carleton.edu>> wrote:
>
>     Hi all,
>
>     I'm seeing some strange behavior with tracing code, which I'd love
>     some
>     help understanding. I've boiled it down to the following
>     simplified example:
>
>     (define count
>        (lambda (n)
>          (if (equal? n 1) 1
>              (+ 1 (count (- n 1))))))
>
>     ,tr (count 92)
>
>
>     When I run the above code (in a fresh Guile instance, via redirecting
>     from a file), the trace runs to completion.
>
>     However, when I run this version of the code from a file, which
>     runs the
>     function twice...
>
>     (define count
>        (lambda (n)
>          (if (equal? n 1) 1
>              (+ 1 (count (- n 1))))))
>
>     ,tr (count 10)   ; runs to completion
>     ,tr (count 92)   ; dies mid-trace
>
>
>     ... then the trace dies when it runs the second time, in something
>     that
>     must be some sort of stack overflow, though the error is fairly
>     cryptic:
>
>     While executing meta-command:
>     In procedure +: Wrong type argument in position 1: #<unspecified>
>
>     What's happening from a memory perspective where tracing the code the
>     first time affects how much memory is available for the second
>     time? It
>     seems that the first run shouldn't affect the stack limit of the
>     second,
>     but something is going on.
>
>     Thanks for the help.
>     Dave
>
>
> I've tried it with Guile 3.0.4 (in macOS) and I didn't get this error. 
> What version of Guile and OS are you using?
>
> Aleix
>