I was thinking about the mapping of / and % and indeed maybe the simplest option is not to map them.
Of course, having an infix syntax would make things easier: 5 % 3 vs 5 rem 3 vs 5.rem(3), in increasing order of typed keys (and visual noise for the latter ?). On the other hand, if there is no mapping I can imagine people keeping asking whether to use mod or rem... -- Matthieu On Thu, Apr 25, 2013 at 6:25 PM, Graydon Hoare <[email protected]> wrote: > On 13-04-25 07:52 AM, Diggory Hardy wrote: > >> My opinion (that nobody will follow, but I still give it) is that integers >>> should not have the "/" operator at all. This was one of the bad choices >>> of >>> C (or maybe of a previous language). >>> >> >> Hmm, maybe, though I can imagine plenty of people being surprised at that. >> >> What really gets me though is that % is commonly called the "mod" >> operator and >> yet has nothing to do with modular arithmatic (I actually wrote a blog >> post >> about it a few months back: [1]). If it were my choice I'd either make "x >> % y" >> do real modular arithmatic (possibly even throwing if y is not positive) >> or >> have no % operator (just mod and rem keywords). >> > > While it's true that people often pronounce % as "mod", the fact is most > of the languages in the lineage we're looking at treat it as "rem". > > http://en.wikipedia.org/wiki/**Modulo_operation<http://en.wikipedia.org/wiki/Modulo_operation> > > 50 languages in that list expose 'remainder' and 19 of them map it to '%'. > As well, as a "systems language", it _is_ salient that the instructions on > the CPUs we're targeting and the code generator IR for said machines (LLVM) > expose a remainder operation, not a modulo one. Of the 35 languages that > expose _anything_ that does "proper mod", only interpreted/script languages > (TCL, Perl, Python, Ruby, Lua, Rexx, Pike and Dart) call it %. That's not > our family. I'm sorry; if we're arguing over "what the % symbol means", it > means remainder in "our" language family (the one including C, C++, C#, D, > Go, F#, Java, Scala). > > (more gruesome comparisons available here: http://rigaux.org/language-** > study/syntax-across-languages/**Mthmt.html#MthmtcDBQAM<http://rigaux.org/language-study/syntax-across-languages/Mthmt.html#MthmtcDBQAM>) > > There are other questions to answer in this thread. We had a complex set > of conversations yesterday on IRC concerning exposure of multiple named > methods for the "other variants" -- ceiling, floor and truncating division, > in particular. We may need to expose all 3, and it might be the case that > calling any of them 'quot' is just misleading; it's not clear to me yet > whether there's a consistent method _name_ to assign '/' to (floating point > divide seems to do the opposite of integer divide on chips that have both). > > But I don't think it's wise to map % to 'mod' if we're exposing both 'mod' > and 'rem'. That's a separate issue and one with (I think) a simpler answer > for us. > > -Graydon > > > ______________________________**_________________ > Rust-dev mailing list > [email protected] > https://mail.mozilla.org/**listinfo/rust-dev<https://mail.mozilla.org/listinfo/rust-dev> >
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