Issue #20974 has been updated by mame (Yusuke Endoh). Discussed at the dev meeting. @matz said that it should return `[[:opt]]` instead of `[[:opt, nil]]`. ---------------------------------------- Bug #20974: Required and optional anonymous parameter show differently in Proc#parameters https://bugs.ruby-lang.org/issues/20974#change-111394 * Author: alanwu (Alan Wu) * Status: Open * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- The following has had the same output since Ruby 1.9, when Proc#parameters was [introduced]: ```ruby p(proc { |(_a)| }.parameters) # => [[:opt, nil]] p(lambda { |(_a)| }.parameters) # => [[:req]] ``` I think they should be `[[:opt]]` and `[[:req]]` or `[[:opt, nil]]` and `[[:req, nil]]`. I prefer the nil-free option since that feels more anonymous. [introduced]: https://docs.ruby-lang.org/en/master/NEWS/NEWS-1_9_2.html -- https://bugs.ruby-lang.org/