A very valid wish. I asked Chris Haynes; my recollection of his
comments were:
- Type puns lead to bugs.
- Separating booleans from lists makes Scheme more amenable to static
type analysis.
- It's possible to construct an interpreter that can switch modes.
(They apparently didn't consider the possibility of a single
interpreter running in both modes simultaneously.)
These seem pretty controversial to me, but let's please not debate the
quality of these reasons on the Guile list; comp.lang.scheme would be
more appropriate.