Enumerator::Lazy missing filter_map and with_index methods

[ivoanjo]

Hello, hello 👋

I'm again spending a few minutes trying to get @DataDog's ddtrace gem specs going with TruffleRuby and I've noticed that Enumerator::Lazy is missing a few more methods (beyond those fixed in #2273), which forces lazy enumerators to become eager (non-lazy). The impact can be that, of course, if you do that with an infinite enumerator, the app will break (and in general it breaks the expected semantics).

In particular, the following are still not lazy on TruffleRuby:

• filter_map

# truffleruby 21.1.0, like ruby 2.7.2, GraalVM CE Native [x86_64-darwin]
[10] pry(main)> [1].lazy.filter_map(&:zero?)
=> []
# ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [x86_64-darwin19]
[7] pry(main)> [1].lazy.filter_map(&:zero?)
=> #<Enumerator::Lazy: ...>

• with_index

# truffleruby 21.1.0, like ruby 2.7.2, GraalVM CE Native [x86_64-darwin]
[19] pry(main)> [1].lazy.with_index(&:+)
=> [1]
# ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [x86_64-darwin19]
[14] pry(main)> [1].lazy.with_index(&:+)
=> #<Enumerator::Lazy: ...>

[eregon]

Thank you for the report. @bjfish Could you look at this?

[eregon]

As a note, it seems both of these methods are new as of Ruby 2.7.

[bjfish]

These methods have been implemented at:
3c68160
e6e7a0e

[ivoanjo]

Thanks @bjfish for looking into this 🙇