lazy-from (Lazy.from)

Tired of needing to convert all your iterables to an Array (with Array.from or spread syntax) just to use map, filter, concat, flat, includes, etc? Maybe .filter().map() is allocating extra arrays every time you chain them and you have like a billion elements so that's slow?

Use Lazy.from. It's just like Array.from but no conversion to arrays and more features (zip, toSet, take, plus more).

Lazy.from([1,2,3])
    .map(x => x*3)
    .filter(x => x%2==0)
    .map(x => `${x}`)
    .concat([10, 11])
    .concat((function*(){ yield 2; yield* "hello"; })())

• no dependencies (I might add an optional dependency of some typescript type helpers)
• written in TypeScript with well-cared-for types. Might add a version that doesn't require typescript@^4.0
• feel free to contribute fixes and new useful methods
• written using anonymous generator objects in JavaScript which make the codebase tiny and neat, check them out

Disclaimer

Don't expect performance to be better! .filter/.map is commonly hyper-optimized by the runtime so it can very easily out perform custom generator code. In some cases yes, this can be more performant, but generally if you're looking for performance, not ergonomics, try to use Array.prototype functions well for high performance.