Re: Stop UNDEF exceptions

[Chris Warburton]

Commit 808042f restores the 'undefined' template stuff, and we have a
new script 'listUndefined.rkt' which look through the sample for
destructor-functions, finds the type which defines the associated
destructor, finds all of its constructors, discards the one that's
handled by that destructor-function, and turns all of the others into
patterns suitable for inserting into the template.

So far we don't actually know that these patterns should look like, so
we need to do some trial and error, and update the script accordingly.