On Tue, Oct 2, 2012 at 9:39 AM, Carl Eastlund <c...@ccs.neu.edu> wrote: > I'm not surprised, I pretty much expected this response, but I'm curious > what the difficulty was. Is cond-as-void relied on that much more > pervasively than mutable pairs?
I'm not sure I can comment on the relative reliance, but in the case of mutable pairs, we had a lot at stack (ie many abstractions are broken in their presence). That's not the case with the cond/void situation. > Is it exceedingly hard to add else-clauses > to all the necessary conds? You two, Robby and Matthew, probably have a > better idea than I do about the prevailing trends in the Racket code base. I don't think we considered writing a script to stick else clauses in. We just were surprised at how often it was relied on and decided to give up. (But memory is a fragile thing, so I could be getting this completely wrong.) Robby > Carl Eastlund > > > On Tue, Oct 2, 2012 at 10:36 AM, Robby Findler <ro...@eecs.northwestern.edu> > wrote: >> >> IIRC, we even experimented with this one briefly and quickly gave up >> as we got overwhelmed. >> >> Robby >> >> On Tue, Oct 2, 2012 at 9:22 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote: >> > I think this a great change for a future `racket2' (someone should be >> > keeping a list of these), but it's too incompatible a change for `cond' >> > in `racket'. >> > >> > At Tue, 2 Oct 2012 09:52:38 -0400, Carl Eastlund wrote: >> >> I often wish cond would raise an exception if all the tests failed and >> >> there were no else clause. I have taken to writing a macro to enforce >> >> this; I usually call it cond!. The void default for cond seems like an >> >> un-Racketish holdover from primarily-imperative programming. With some >> >> of >> >> the other changes we've made in Racket, are we willing to consider >> >> changing >> >> the fall-through behavior of cond? It seems like an experiment worth >> >> running to me. >> >> >> >> If not, I would at least like to add an erroring version of cond >> >> somewhere >> >> in the language. It's a shame to have to keep writing such a primitive >> >> feature. Right now in my dracula github repo I have cond! implemented >> >> in >> >> racket/cond and re-exported from racket, but I'm not thrilled about >> >> either >> >> the location or the name. I kept it out of racket/base so I could >> >> depend >> >> on the syntax collection for good source location reporting in the >> >> error >> >> message. >> >> >> >> Carl Eastlund >> >> _________________________ >> >> Racket Developers list: >> >> http://lists.racket-lang.org/dev >> > _________________________ >> > Racket Developers list: >> > http://lists.racket-lang.org/dev >> > _________________________ Racket Developers list: http://lists.racket-lang.org/dev
