Per Bothner scripsit:

> In that case they're not essential in the *language*. I find singularly
> unpersuasive arguments that we need something in the language because
> it is useful to a debugger.  A useful debugger has to go beyond the
> language.  For example a debugger should be able to inspect function-local
> and non-exported module variables.

A classical Lisp debugger is not in the general case a programmer's
debugger.  It notifies the user that something goes wrong and provides
a variety of options for recovery, described in a high-level way (in
English or another natural language, typically).  To make this work, we
need restarts, which is something the large language ought IMHO to have.

CL: http://www.ai.mit.edu/projects/iiip/doc/CommonLISP/HyperSpec/Body/sec_9-1-4-2.html

MIT: http://www.gnu.org/software/mit-scheme/documentation/mit-scheme-ref/Restarts.html

Riastradh: http://mumble.net/~campbell/proposals/restart.text

--
John Cowan    cowan@ccil.org    http://ccil.org/~cowan
This great college [Trinity], of this ancient university [Cambridge],
has seen some strange sights. It has seen Wordsworth drunk and Porson
sober. And here am I, a better poet than Porson, and a better scholar
than Wordsworth, somewhere betwixt and between.  --A.E. Housman

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