Free constraint software developed by Institute for New Generation Computer Technology (ICOT), Japan: Constraint MGTP (CMGTP) model generation theorem prover (MGTP), MGTP-G, KLIC, some cu-Prologs, and documents. FTP site.
A paper by Will Clinger (1991) which describes an alternative to the low-level macro facility described in the R4RS. The macrology is based upon the explicit renaming of identifiers.