so that no derivation data structure creation
happens during just a normal judgment-holds,
but this was not entirely successful, so there
still is some....
Also, improved the test-util to show stacktraces
for errors (when they exist)
included in the compiled files. (also, misc minor cleanups
notably a new exercise in tut.scrbl)
closes PR 12547 --- there are still a few uses left, but they do not
seem to be coming from Redex proper:
- /Users/robby/git/plt/collects/racket/private/map.rkt still appears
in a bunch of places (there is a separate PR for that I believe),
and
- /Users/robby/git/plt/collects/redex/../private/reduction-semantics.rkt
appears in tl-test.rkt, but I do not see how it
is coming in via Redex code, so hopefully one of the other
PRs that Eli submitted is the real cause. If not, I'll revisit later
redex patterns a bunch:
- repeats are turned into wrappers in sequences,
- names are all explicit,
- non-terminals are wrapped with `nt',
- cross patterns always have the hyphens in them.
- ellipses names are normalized (so there are no "hidden"
name equalities); this also means that repeat patterns
can have both a regular name and a mismatch name
Also, added a match-a-pattern helper macro that checks to make sure
that functions that process patterns don't miss any cases
