Another typical example: ```js const normalizeHue = hue => (((hue % 360) + 360) % 360) / 360; // phew..
// would become: const normalizeHue = hue => (hue %% 360) / 360; ``` On Sat, Aug 17, 2019 at 9:54 PM Isiah Meadows <[email protected]> wrote: > BTW, that very example is something I cover in my proposal's > introduction. It's also part of why I want an operator - this is one > of the few times where spreading FUD *is* a good idea IMHO. > https://github.com/isiahmeadows/proposal-divisor-dependent-modulo/ > > ----- > > Isiah Meadows > [email protected] > www.isiahmeadows.com > On Fri, Aug 16, 2019 at 12:33 PM Alex Gordon <[email protected]> > wrote: > > > > Code that uses % is often surprisingly buggy. For example even a simple > function such as this is broken if n is negative: > > > > function isOdd(n) { > > return n % 2 === 1; > > } > > > > isOdd(-3) // false > > > > The same is not true in other programming languages. The same in Python > works just fine: > > > > def isOdd(n): > > return n % 2 == 1 > > > > isOdd(-3) // true > > > > The advantage of an operator over a function is that it allows us to say > to people who are new to JS: "Always use %% instead of % unless you have a > good reason". Just the same as we say "Always use === instead of == unless > you have a good reason". > > > > > > On Thu, Aug 15, 2019 at 10:01 PM Isiah Meadows <[email protected]> > wrote: > >> > >> BTW, I just wrote up a more precise, formalized proposal over here: > >> https://github.com/isiahmeadows/proposal-divisor-dependent-modulo/, > >> and I'd be more than willing to work with a TC39 champion on it. I > >> personally prefer syntax (pretty strongly), but I'm not beholden to > >> it. > >> > >> I do feel the semantics are simple enough it'd be okay to lower it to > >> syntax, and it naturally just glides right in. I find it *very* odd > >> that some languages use a simple operator `%` or relatively short > >> function for remainder keeping the sign of the dividend but relegate > >> the version keeping the sign of the divisor (the more useful and > >> intuitive of them) to a much more verbose function call. Of all > >> Wikipedia lists in https://en.wikipedia.org/wiki/Modulo_operation, > >> here's the four that do this currently - all but one expose an > >> operator for the first: > >> > >> - Fortran: `mod` for dividend-dependent, `modulo` for divisor-dependent > >> - Julia: `%`/`rem` for dividend-dependent, `mod` for divisor-dependent > >> - Java: `%` for dividend-dependent, `Math.floorMod` for > divisor-dependent > >> - XBase++: `%` for dividend-dependent, `Mod` for divisor-dependent > >> > >> And it's worth noting most other languages (including some end > >> user-oriented ones) that show a syntactic preference to one or the > >> other expose a simpler one where the sign matches the divisor, a more > >> complicated one where the sign matches the dividend. For a variety of > >> examples: > >> > >> - Ruby: `%`/`modulo` for divisor-dependent, `remainder` for > dividend-dependent > >> - SML: `mod` for divisor-dependent, `Int.rem` for dividend-dependent > >> - Elm: `modBy` for divisor-dependent, `remainderBy` for > dividend-dependent > >> - Euphoria: `mod` for divisor-dependent, `remainder` for > dividend-dependent > >> - Python: `%` for divisor-dependent, `math.fmod` for dividend-dependent > >> - Smalltalk: `\\` for divisor-dependent, `rem:` for dividend-dependent > >> > >> And of course, many don't even expose a type of modulo where the sign > >> matches the divisor. For some examples: > >> > >> - APL > >> - LibreOffice/Excel > >> - Lua > >> - Perl > >> - Mathematica > >> - PL/I > >> - TCL > >> > >> There's also Dart, a relatively new language which defaults to > >> non-negative always. > >> > >> This relatively long list of languages, *despite* C's heritage and > >> semantics being inherited in much of them, makes me question using a > >> function for this, and there would need to be a *lot* of FUD to get > >> people to use the function more than the operator. > >> > >> So this is why I would prefer an operator as opposed to syntax for this. > >> > >> ----- > >> > >> Isiah Meadows > >> [email protected] > >> www.isiahmeadows.com > >> > >> On Thu, Aug 15, 2019 at 3:58 PM Jordan Harband <[email protected]> > wrote: > >> > > >> > Static functions don't have the same risk as prototype functions; > `Math.mod` would make sense to add. > >> > > >> > One suggestion, though, would be to try to add the API method first, > and look at usage for awhile before trying to add the syntax. > >> > > >> > On Thu, Aug 15, 2019 at 10:12 AM Andrea Giammarchi < > [email protected]> wrote: > >> >> > >> >> To me there's no risk, as MooTools, Prototype, and Scriptacolous are > both things of the past, and never implemented Math.mod ... so, with that > approach, custom transpiling functions are more dangerous, as somebody > might have implemented `%%` already for other purposes, and we break Babel > outcome adding new syntax anyway ... the smoosh accident, is the equivalent > of custom Babel utilities these days. > >> >> > >> >> Look at TypeScript and the private class fields, if you want to > compare new syntax instead > >> >> > >> >> On Thu, Aug 15, 2019 at 4:50 PM Michael Haufe < > [email protected]> wrote: > >> >>> > >> >>> Thursday, August 15, 2019 2:47 AM, Andrea Giammarchi wrote: > >> >>> > >> >>> > >> >>> > >> >>> > FWIW another disadvantage is that operators cannot be polyfilled, > so it'll take forever for those not using transpilers to adopt these, while > having a `Math,mod` would work right away > >> >>> > >> >>> > >> >>> > >> >>> > >> >>> > >> >>> With such an approach there is risk of another ‘smooshgate’ [1][2]. > There is nothing stopping those developers from using a function anyway to > bridge the gap if they can’t or won’t use a compiler. This is already the > current state of affairs. > >> >>> > >> >>> > >> >>> > >> >>> [1] https://developers.google.com/web/updates/2018/03/smooshgate > >> >>> > >> >>> [2] > https://adamsilver.io/articles/the-disadvantages-of-javascript-polyfills/ > >> >>> > >> >>> > >> >>> > >> >>> Michael > >> >> > >> >> _______________________________________________ > >> >> es-discuss mailing list > >> >> [email protected] > >> >> https://mail.mozilla.org/listinfo/es-discuss > >> > > >> > _______________________________________________ > >> > es-discuss mailing list > >> > [email protected] > >> > https://mail.mozilla.org/listinfo/es-discuss > >> _______________________________________________ > >> es-discuss mailing list > >> [email protected] > >> https://mail.mozilla.org/listinfo/es-discuss > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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