This page is part of the web mail archives of SRFI 52 from before July 7th, 2015. The new archives for SRFI 52 contain all messages, not just those from before July 7th, 2015.
Welcome to the SRFI-52 mailing list. Let me begin by pointing out that while the current official draft of SRFI-52 is at the usual place (srfi.schemers.org), between submissions of drafts I will be keeping more recent text available at: http://regexps.srparish.net/srfi-drafts/permitting-unicode.srfi The changes so far are quite minor. As additional changes are made I'll announce those on this list. There is a short story behind this SRFI. I'm currently helping to design and build a new implementation called Pika Scheme. Among the goals for this implementation is that is have good support for Unicode. For example, I want to be able to represent Unicode characters[*] as CHAR? values, Unicode strings as STRING? values, and allow programmers to write identifiers in their programs using Unicode characters. While working on that I noticed (as have some others) that some of the requirements of R5RS can not be satisfied in a natural way by a Unicode implementation. The largest source of problems concerns case mapping: R5RS has a relatively naive view of the nature of upper and lowercase characters -- a view that does not model Unicode well. These problematic R5RS requirements effect some standard procedures and the definition of "identifier equivalence". There effect is particularly noticable in portable Scheme programs that attempt to process Scheme s-expression syntax. So, I became interested in looking for ways to "fix" R5RS -- to change the requirements so that Unicode implementations could more easily comply. In the spirit of the Revised Report, I want my proposed changes to be small, to not be specific to Unicode, to not complicate the report needlessly, to be as upwards compatible as possible, and ideally to be easy to implement in an implementation which already conforms to R5RS. Concurrently with working on that, I've also been working on specifying the particular CHAR? and STRING? type that will be used in Pika Scheme. To provide some context, I've made available some of those other specifications at: http://regexps.srparish.net/srfi-drafts/INDEX.html I've written the other specifications in the _form_ of draft SRFIs, however it is currently far too early to submit any of them to the SRFI process. -t [*] What exactly is a "Unicode character?" The answer can vary depending on context. In some contexts it might mean a Unicode abstract character -- the kind of value to which a codepoint (integer in the range 0..10ffff) is assigned. In other contexts, it may mean certain kinds of sequences of abstract characters. One goal for SRFI-52 is to remain agnostic about the answer to that question.