On Sun, Feb 19, 2012 at 7:10 PM, Neil Toronto <neil.toro...@gmail.com> wrote: > On 02/19/2012 06:05 AM, Robby Findler wrote: >> >> On Sun, Feb 19, 2012 at 12:30 AM, Gary Baumgartner<g...@cs.toronto.edu> >> wrote: >>> >>> On a more productive note: in Racket code I define and use 'implies' a >>> lot, >>> often conjoined, for predicates. It's mainly of declarative value, which >>> is >>> perhaps why it's uncommon in implementation despite how common it is in >>> specification. And for boolean expressions in general I also use >>> 'neither'. >>> Are these something that others [would] use and so could be added to >>> Racket's >>> library? >> >> >> Seems to me adding implies, nand, and nor to racket/bool is a good idea. >> >> Let me know if you disagree (and if you disagree after I've already >> committed, it is a simple thing to drop the commit or change it). > > > I've occasionally written my own `implies', but never make it shortcut like > `and' and `or'. Speaking of which, would it handle more than two arguments? > One? Zero? What kind of associativity would be appropriate?
The version I checked in shortcuts in an implication-appropriate way (if the first argument is #f). I think the convention (due to functions and currying) is pretty well established that it associates to the right. So that's what the version I checked in does for the 3+ argument case. I didn't see something reasonable for the 0 or 2-ary case so it doesn't handle them. > Bwahaha. :) I'm still pondering those questions for xor. :) Robby ____________________ Racket Users list: http://lists.racket-lang.org/users
