[clean-list] Passing an environment around

[Richard A. O'Keefe]

I note that one of the features of the O'Caml system is that it has a
preprocessor interface where you can plug in the syntax of your choice
(if I've understood the manual right).  And the hbc compiler for Haskell
from Chalmers is "really" the LML compiler with a different parser.

Perhaps the Clean team might consider providing something like O'Caml's
front end so that people could experiment with different syntaxes (e.g.,
one that uses if _ then _ else) while still taking advantage of a great
compiler.