[racket] Help On User Libraries - The Basics

Good stuff to know.   Thx.

On Sun, Aug 21, 2011 at 6:06 PM, Eli Barzilay <eli at barzilay.org> wrote:

> 6 hours ago, Ray Racine wrote:
> >
> > Fire up my repl with the path to my personal collection and invoke.
> > [ray at ray rktlib]$ rlwrap /usr/local/racket/bin/racket -i  -S
> /code/rktlib
>
> If you're working on a shell it would be better to use readline -- but
> since you're using the git head, it's even better to use the new
> `xrepl'.  Just add (require xrepl) to your ~/.racketrc, and you'll get
> readline and an additional bunch of tools for REPL-use.
>
>
> > In the old days it seemed I generally got an accurate error line and
> > stack trace.  In the above error, I'm pretty sure the error is
> > occurring in the "worker" for-each which is not lexically near line
> > 194.  The context information is less than helpful in the sense that
> > misc.rkt:87 is the repl's invoke and then the next thing I'm given
> > is the for-loop error.  All in all a rather thin context to work
> > with.
>
> The stack information that you see is imprecise in the sense that
> Matthew mentioned, and indeed errortrace compiles code with explicit
> annotations so that you get precise information.  (But that comes at a
> runtime overhead.)  With DrRacket, you get the extra errortrace
> information when you have the debugging option on.
>
>
> > I've tried to ask racket to provide a full stack trace with things
> > like adding '-l errortrace' when invoking racket, but to no avail.
> > So next question, how do I compel racket to provide the full call
> > stack on errors?
>
> When you add that flag you do get errortrace, but then it's tricky to
> get the rest.
>
>  racket -l errortrace
>
> you get no REPL -- need to add a -i flag:
>
>  racket -l errortrace -i
>
> you get a REPL, but it has no useful binding -- you're missing the
> language, so add `racket/init' too
>
>  racket -l errortrace -l racket/init -i
>
> which finally works.  Alternative shorter syntax for that:
>
>  racket -lli errortrace racket/init
>
> And if you're using `xrepl', you get a command that turns on
> errortrace: ",errt".
>
> (But as Matthew said, all of this depends on compiling code in an
> "errortrace mode" so if you precompile your files, you don't get the
> extra information.)
>
> --
>          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
>                    http://barzilay.org/                   Maze is Life!
>
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