Scheme 48 is an implementation of the Scheme programming language as
described in the Revised^4 Report on the Algorithmic Language Scheme.
It is based on a compiler and interpreter for a virtual Scheme
machine.  The name derives from our desire to have an implementation
that is simple and lucid enough that it looks as if it were written in
just 48 hours.  We don't claim to have reached that stage yet; much
more simplification is necessary.

Scheme 48 tries to be faithful to the upcoming Revised^5 Scheme
Report, providing neither more nor less in the initial user
environment.  (This is not to say that more isn't available in other
environments; see below.)  Support for numbers is weak: bignums are
slow and floating point is almost nonexistent (see description of
floatnums, below).  DEFINE-SYNTAX, LET-SYNTAX, LETREC-SYNTAX, and
SYNTAX-RULES are supported, but not the rest of the Revised^4 Scheme
macro proposal.