Path: utzoo!attcan!uunet!husc6!uwvax!rutgers!bellcore!tness7!killer!pollux!ti-csl!mips!gateley From: gateley@mips.csc.ti.com (John Gateley) Newsgroups: comp.lang.scheme Subject: Re: collect special form for streams Message-ID: <50472@ti-csl.CSNET> Date: 31 May 88 21:01:46 GMT References: <294@gt-eedsp.UUCP> Sender: root@ti-csl.CSNET Reply-To: gateley@mips.UUCP (John Gateley) Distribution: na Organization: TI Computer Science Center, Dallas Lines: 14 Posted: Tue May 31 16:01:46 1988 In article <294@gt-eedsp.UUCP> schw@gt-eedsp.UUCP (Dave Schwartz) writes: >How can the "collect" special form for streams (from Chap. 3 of >Structure and Interpretation of Computer Programs) be implemented for >TI PC-Scheme? I have Kent Dybvig's "extend-syntax," but this does not >appear to be powerful enough for this special form. Extend-syntax's pattern matching is not powerful enough to do this. You have to use the "with" feature to generate the v functions. (by calling a function which builds them, i.e. you do them by hand). I also used a help macro to make the flatmap parts of the expression (watch out for keywords). If this is not enough help, email me and I will send you my code. John Gateley gateley@tilde.csc.ti.com