Re-implement List.map in pure elm

[fredcy]

See discussion at https://groups.google.com/forum/#!topic/elm-dev/He_emRjsly8

The objective is to build a pure-Elm version of map that has good performance for shorter lists and avoids stack overflow for long lists.

There are benchmarks at https://github.com/fredcy/elm-core-benchmark.

[process-bot]

Thanks for the pull request! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[process-bot]

Thanks for the pull request! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.

[evancz]

Based on your work, @Skinney created #872 which applied this technique to foldr and then implemented map in terms of that. He had some benchmarks that were pretty easy to run, so I played with those to tune the size vs speed.

Point is, map is implemented in Elm now through that! Sorry it took so long to get an answer on this, and thank you for the work! Turned out we could move a bunch of things into Elm with this!

[evancz]

Based on your work, @Skinney created #872 which applied this technique to foldr and then implemented map in terms of that. He had some benchmarks that were pretty easy to run, so I played with those to tune the size vs speed.

Point is, map is implemented in Elm now through that! Sorry it took so long to get an answer on this, and thank you for the work! Turned out we could move a bunch of things into Elm with this!