S9fES is a mature, portable, and comprehensible interpreter for the R4RS Scheme programming language. It offers the following features:
S9fES has been placed in the public domain by its author. Because the author no longer hosts the code, it is made available here.
The internal structure of the interpreter is documented in detail in the book Scheme 9 from Empty Space. An obsolete version of the book is available for free.
The original author can be reached at n m h @ t 3 x . o r g (Hint, include his first name in the subject), please direct questions regarding this mirror to firstname.lastname@example.org