syntax-case
SYNTAX-CASE is a system for macros proposed by R. Kent Dybvig in 1992 for Scheme (see "Syntactic Abstraction in Scheme", IUCS TR #355, link below), which generalises Common LISP's DEFMACRO and Scheme's SYNTAX-RULES (a hygienic macro facility defined in the R5RS Scheme standard), and which cannot be defined in terms of either.

It is controversial whether or not Common LISP would benefit from the addition of SYNTAX-CASE, and no implementations of SYNTAX-CASE for Common LISP are known of.

External links:

  1. IUCS-TR-355 [ps.gz]. Syntactic Abstraction in Scheme. Hieb, Dybvig and Bruggeman, Indiana University, 1992.
  2. IUCS-TR-356 [ps.gz]. Writing Hygienic Macros in Scheme with Syntax-Case. Dybvig, Indiana University, 1992.
  3. FOLDOC on SYNTAX-CASE

language extension