Hello Mark, Thanks for your answer, and I see your point concerning the non-readability of EOF.
And by the way, this point is not so obvious, contrary to what the doc says: > > Macro: /SCM/ *SCM_EOF_VAL* > > The Scheme end-of-file value. It has no standard written > representation, for obvious reasons. > If Guile would read port using stdio rather that libguile/ports, there would be no problem in reading #<eof>, which is just the immediate value 2564. Best, Pierre On 02/07/2016 04:39, Mark H Weaver wrote: > Hi, > > Pierre Lairez <[email protected]> writes: > >> I understand why we cannot use (eof-object) in a “case” statement. For >> example, this will not run as it is meant: >> (case (get-char port) >> (((eof-object)) ...) >> (else ...)) >> >> Is is possible to define something like #eof that will be datum and make >> the following work as expected? >> (case (get-char port) >> ((#eof) ...) >> (else ...)) > We cannot make a 'read'able datum that is an eof object, because of the > API of 'read'. When 'read' returns an eof object, that means that the > end of file has been reached, and that's how existing callers of 'read' > will interpret such a result. > > I would suggest using (ice-9 match) instead, e.g.: > > (match (get-char port) > ((? eof-object?) 'eof) > ((or #\a #\b) 'a-or-b) > (#\c 'c) > (char 'other-character)) > > See section 7.7 (Pattern Matching) in the Guile manual. > Does that work for you? > > Regards, > Mark
signature.asc
Description: OpenPGP digital signature
