(that was assuming Ryan's assertion that "[...]Matthew say that he would have used a keyword for `else` in `cond` if he had it to do over again", which seem to mean that even in Racket2 Matthew would prefer `#:else' over `[else ...]' ?)
On Sat, May 4, 2013 at 5:14 PM, Laurent <laurent.ors...@gmail.com> wrote: > Matthew, > Out of curiosity, could you explain why you'd prefer #:else everywhere > instead of [else ...] ? > Would such an #:else allow for multi-line bodies? > > > On Sat, May 4, 2013 at 5:06 PM, Matthew Flatt <mfl...@cs.utah.edu> wrote: > >> At Sat, 4 May 2013 09:15:22 -0500, Robby Findler wrote: >> > On Sat, May 4, 2013 at 9:07 AM, Matthew Flatt <mfl...@cs.utah.edu> >> wrote: >> > >> > > At Fri, 3 May 2013 17:29:52 -0400, Eli Barzilay wrote: >> > > > A few minutes ago, Robby Findler wrote: >> > > > > >> > > > > FWIW, this was the bug in redex that prompted me to send this >> > > > > message (it was there for some time since it wasn't a syntax error >> > > > > .... it was similar in spirit to the code I posted; things broke >> > > > > when #f was an argument) >> > > > >> > > > [I think that it's good to have a much more relaxed policy about >> > > > breaking compatibility in cases like this: so far there was no real >> > > > code found that uses the feature, but there is one instance of code >> > > > that would get fixed by the change...] >> > > >> > > Well, Ian provided an example from real code, right? Ian is willing to >> > > change his code, but the code sounds real. >> > > >> > > There's also the use in `unparse-pattern' in Redex. Maybe that's the >> > > troublesome one that Robby has in mind changing (or he would be happy >> > > to change it, obviously), but it's another real example. >> > > >> > > >> > No, that was not the example. The code I sent at the beginning of the >> > thread was an adjusted version of the bug that hid in Redex for, >> roughly, >> > months. It was a real bug and caused real problems and we knew something >> > was wrong but didn't find it for some time. >> > >> > In other words, this isn't some made-up, code cleanliness-based request. >> >> Yes, I understand that you faced a real bug. I hedged above on >> `unparse-pattern' not to suggest that your actual bug was >> uninteresting, but to suggest that I might misunderstand the >> relationship between the bug and the current state of our repository. >> >> All else being equal, I'm definitely in favor of a change to a sensible >> `else' for `match'. The "else" that isn't equal, however, is backward >> compatibility, and I think we're at the right point in our development >> cycle to defer backward incompatibilities to the next language --- >> hence my vote to defer. >> >> _________________________ >> Racket Developers list: >> http://lists.racket-lang.org/dev >> > >
_________________________ Racket Developers list: http://lists.racket-lang.org/dev
