I'm not saying we should add it on to that proposal, but rather saying that I think more effort should be put into a standard library where things like this don't need to go through a full standards process. That's just my opinion, and borderline on-topic for this specific suggestion.
I'm absolutely in favor of having a `range` method, it's just _where_ it should be that I differ. Jacob Pratt On Thu, Nov 29, 2018 at 4:29 AM Jack Works <[email protected]> wrote: > Oh, I'm not here to find out how to implement a range in detail. That's > the trivial things, I want to first make it become a stage 0 proposal, then > we can discuss if we need some overload or how to deal with the edge cases. > Ps, does Pratt mean we should add it as a standard library in the stage 1 > standard libraray proposal? > > On Thu, Nov 29, 2018, 12:18 Jacob Pratt <[email protected]> wrote: > >> Quick, simple TypeScript range function (with overloads, of course). >> >> ``` >> export function range(end: number): IterableIterator<number>; >> export function range(start: number, end: number): >> IterableIterator<number>; >> export function range(start: number, end: number, step: number): >> IterableIterator<number>; >> export function* range(start: number, end?: number, step?: number): >> IterableIterator<number> { >> // overload #1 >> if (end === undefined) { >> [start, end, step] = [0, start, 1]; >> } >> >> // overload #2 >> if (step === undefined) { >> step = Math.sign(end - start); >> } >> >> // ensure we have the appropriate types >> if (typeof start !== 'number' || typeof end !== 'number' || typeof step >> !== 'number') { >> throw new TypeError('all parameters must be of type number'); >> } >> >> while ((start < end && step > 0) || (start > end && step < 0)) { >> yield start; >> start += step; >> } >> } >> ``` >> >> IMO, we should focus on building up a JavaScript standard library that >> has tons of useful utilities like this, rather than continue to add methods >> onto namespaces. Perhaps that's just me, though. >> >> Jacob Pratt >> >> On Wed, Nov 28, 2018 at 9:33 PM Tab Atkins Jr. <[email protected]> >> wrote: >> >>> I end up writing a range function in virtually every project I use, so >>> yeah, I think this is worthwhile. >>> >>> My own preferences, based on Python precedence: >>> >>> Number.range(end) === Number.range(0, end, 1) >>> Number.range(start, end) === Number.range(start, end, >>> Math.sign(end-start)) >>> Number.range(start, end, step) => { >>> if start < end && step > 0: yield all (start + k*step), for k from 0 >>> to infinity, less than end >>> elif start > end && step < 0: yield all (start + k*step), for k from >>> 0 to infinity, greater than end >>> else: yield nothing >>> } >>> >>> So: >>> * [...Number.range(5)] evaluates to [0, 1, 2, 3, 4] >>> * [...Number.range(0)] evaluates to [] >>> * [...Number.range(-5)] evaluates to [] >>> * [...Number.range(1, -3)] evaluates to [1, 0, -1, -2] >>> * [...Number.range(-3, 1)] evaluates to [-3, -2, -1, 0] >>> * [...Number.range(1, 1)] evaluates to [] >>> * [...Number.range(0, 10, 5)] evaluates to [0, 5] >>> * [...Number.range(0, 10, -5)] evaluates to [] >>> >>> ~TJ >>> >> _______________________________________________ >>> es-discuss mailing list >>> [email protected] >>> https://mail.mozilla.org/listinfo/es-discuss >>> >>
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