String reversing supporting astral characters and combining unicode chars

[eoftedal]

Code borrowed from @mathiasbynens:
https://github.com/mathiasbynens/esrever/blob/master/esrever.js

[eoftedal]

Partial fix of: https://github.com/elm-lang/core/issues/625

[eoftedal]

Partial fix of: https://github.com/elm-lang/core/issues/625

[lukewestby]

@eoftedal what are the performance effects of this change?

[lukewestby]

@eoftedal what are the performance effects of this change?

[et]

Awesome @eoftedal! Shouldn't there also be a test here?

[et]

Awesome @eoftedal! Shouldn't there also be a test here?

[Pilatch]

If there are performance implications, which I'd bet there are, maybe this could instead become another function.

[Pilatch]

If there are performance implications, which I'd bet there are, maybe this could instead become another function.

[eoftedal]

To be honest, I don't know the performance implications. I also don't know if people use a string reversing function enough that that matters. I can't really think of many valid use cases for it.

[eoftedal]

To be honest, I don't know the performance implications. I also don't know if people use a string reversing function enough that that matters. I can't really think of many valid use cases for it.

[eoftedal]

Array.from(str).length seems to be about 10 times slower than str.length

[eoftedal]

Array.from(str).length seems to be about 10 times slower than str.length

[eoftedal]

[...str].length seems to be about twice as fast as Array.from(str).length

[eoftedal]

[...str].length seems to be about twice as fast as Array.from(str).length

[evancz]

Fixed in elm-lang@8ca9c38 with proof that speed is equal or faster here and tests in elm-lang@d796fca.

[evancz]

Fixed in elm-lang@8ca9c38 with proof that speed is equal or faster here and tests in elm-lang@d796fca.