Scheme Request for Implementation 262, "Extensible pattern matcher", by Daphne Preston-Kendal, is now available for discussion.
Its draft and an archive of the ongoing discussion are available at https://srfi.schemers.org/srfi-262/. You can join the discussion of the draft by filling out the subscription form on that page. You can contribute a message to the discussion by sending it to srfi-...@srfi.schemers.org. Here's the abstract: A pattern matching form which can operate on arbitrary Scheme values is defined. It conforms to the following design principles. The syntax of patterns is declarative. The syntax is extensible in the same way that Scheme’s procedural syntax is extensible by macros. For most use cases, the use of the pattern matcher should produce code which is essentially as efficient at run time as equivalent procedural Scheme code would be, assuming a moderately optimizing Scheme implementation. This applies only when the equivalent code is also equivalently correct in terms of handling of error cases (i.e. including all type checks done automatically by the pattern matcher). However, using extension syntax should not cause this principle to be violated (provided the extension syntax is appropriately implemented). Regards, SRFI Editor
