SRFI 93: R6RS Syntax-Case Macros

by Kent Dybvig

status: withdrawn (2006/08/23)


The syntactic abstraction system described here extends the R5RS macro system with support for writing low-level macros in a high-level style, with automatic syntax checking, input destructuring, output restructuring, maintenance of lexical scoping and referential transparency (hygiene), and support for controlled identifier capture, with constant expansion overhead. Because it does not require literals, including quoted lists or vectors, to be copied or even traversed, it preserves sharing and cycles within and among the constants of a program. It also supports source-object correlation, i.e., the maintenance of ties between the original source code and expanded output, allowing implementations to provide source-level support for debuggers and other tools.