On 11-Apr-06, at 6:29 PM, Taylor R. Campbell wrote:

> Since `:' is a special initial, it is also an initial, and
> transitively also a subsequent; it may therefore be used at the end of
> an identifier, according to the rule for <identifier>.

Ouch!  You are right.  And somehow I still didn't see this after
triple checking.  Must have been one of those days.  For the record
Gambit's reader allows colons anywhere in a symbol except the end.

So this means that the prefix and postfix syntaxes are equally non
R5RS conformant.  Nevertheless I have rarely seen the colon used at
the end of an identifier, except when the identifier is used
similarly to what keyword objects are used for (i.e. it is used as
data, not as a variable name).  So changing the type of foo: from
symbol to keyword will likely have little effect on such programs.

Marc