I've had an idea to implement a #lang that would provide some syntactic extensions akin to those provided by the Kawa Scheme, particularly with regard to the usage of a colon.
In particular, in Kawa: - the sequence "x:" will be read as a keyword equivalent to #:x - the sequence "a:b" will be read as ($lookup$ a `b) - likewise, the sequence "a:b:c" will be read as ($lookup$ ($lookup$ a `b) `c) and so on - if two colons appear in a row, as in, say "a::b", they will be treated as a separate token, i.e. (call-with-input-string "a::b" read) will return the symbol a and (call-with-input-string "(a::b)" read) will return the list of three tokens, (a :: b) Kawa treats each pair of colons as a separate token, so (call-with-input-string "(:::::::)" read) returns the list (:: :: :: :) but I would actually prefer to treat a sequence of two or more colons as a single token. In either case, I wonder if someone could guide me how to do this, preferably using Racket's internal machinery that's already out there. I found that atoms in Racket are being read by the "read-symbol-or-number?" procedure from expander/read/symbol-or-number.rkt, but I don't think it is sufficiently tweakable - in particular because if I read a colon, I might have to unread it if I can peek another colon. Is there any simple way out of this situation, or do I have to actually implement a Lisp reader from scratch? (I'd be OK with that, because I already wrote a reader in Kawa that I think I could adapt, but then I'd probably have some questions about dealing with syntax objects. The alternative would be to modify Racket's sources to make the reader API more flexible, e.g. allowing to parameterize expander's "read" with the "read-symbol-or-number" function, which I think would be more in the spirit of Racket, but it would probably also take more time to downstream) Thanks in advance, Panicz -- This group is deprecated and retained as an archive. Racket discussions have moved to the Racket Discourse at https://racket.discourse.group/ . --- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. --- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/racket-users/8aee6d2f-687d-4a98-b72c-a459b041eea0n%40googlegroups.com.
