Demo: adding m[x] notation for indexing

[richcarl]

This is just a proof of concept as a discussion point. We could easily have m[x] notation for looking up a value in a map (and possibly other data types), if we wanted to. It's no different grammatically from how it works in e.g. Python or Javascript.

f(X, Y) ->
    A=#{a => #{1=>a, 2=>b, 3=>c},
        b => #{1=>p, 2=>q, 3=>r},
        c => #{1=>x, 2=>y, 3=>z}},
    A[X][Y].

As people are using maps more and more, I see that there could be a case for adding this syntax now, as an alias for erlang:map_get/2, especially for accessing nested maps. Works in guards as well.

[github-actions]

CT Test Results

    2 files     96 suites   1h 7m 50s ⏱️
2 172 tests 2 123 ✅ 48 💤 1 ❌
2 535 runs  2 484 ✅ 50 💤 1 ❌

For more details on these failures, see this check.

Results for commit 32cbe09.

♻️ This comment has been updated with latest results.

To speed up review, make sure that you have read Contributing to Erlang/OTP and that all checks pass.

See the TESTING and DEVELOPMENT HowTo guides for details about how to run test locally.

Artifacts

• Complete CT logs (Download Logs)
• HTML Documentation (Download HTML Docs)
• Windows Installer

// Erlang/OTP Github Action Bot