[plt-scheme] New PLT Redex available in CVS

By way of introduction:

  PLT Redex is a domain-specific language (embedded in DrScheme) for
  implementing and experimenting with Felleisen/Hieb-style reduction
  systems. It includes a facility for writing down the reduction
  systems in a notation similar to that used in papers and a tool that,
  given reduction system and an initial term, allows you to explore its
  (potentially infinite) reduction graph starting. For details, see
  http://people.cs.uchicago.edu/~robby/pubs/papers/rta2004-mfff.pdf

Recent changes:

  - 18x speedup (for the beginner language test suite benchmark)

  - improved the way in-hole pattern matching works. Got rid of the
    "multiple hole interference" error messages. The in-hole+,
    in-hole*, and in-named-hole+ patterns are gone and in-named-hole
    has one fewer argument. Also, `hole' is no longer implicitly bound.

  - More interesting uses of `in-hole' now work, eg:

      F = (hole v) | (E hole)
      E = F[E] | hole

    and other uses of context decomposition that aren't directly
    involved in reductions.

  - added `in-hole' to the term macro, meaning that you don't have
    unquote to put things back in to the hole on the rhs of a
    reduction.

  - replaced the `replace' function with `plug'. It does the same job,
    but only gets two arguments now.

The new version is available in CVS.

Robby