Issue #21875 has been updated by Hanmac (Hans Mackowiak). there are functions that look for the amount of parameters that gets spooked by this: data = { 'a' => 1, 'b' => 2, 'c' => 3 } data.each &proc {|a,| p a } #=> "a", "b", "c" data.each &lambda {|a,| p a } ["a", 1] ["b", 2] ["c", 3] ---------------------------------------- Feature #21875: Handling of trailing commas in lambda parameters https://bugs.ruby-lang.org/issues/21875#change-116416 * Author: Earlopain (Earlopain _) * Status: Open ---------------------------------------- https://bugs.ruby-lang.org/issues/19107 was accepted, which is about trailing commands in method definitions. lambdas were not explicitly mentioned but I wanted to confirm how they should behave with a trailing comma. Or if a trailing comma should even be accepted for them. It's not clear to me since lambdas sometimes behave like blocks and sometimes more like methods. `->(...) {}` for example is syntax invalid (same as in blocks) but they do check their arity with blocks don't do. If a trailing comma is accepted it can either * be implicit splat like in `foo do |bar,|; end` or `foo do |bar|; end`. It would also mean that the trailing comma is only allowed after a positional argument. * Just be ignored and be accepted in most places like for method definitions. The first option would be rather useless in regards to https://bugs.ruby-lang.org/issues/19107 when you just want to add the comma for cleaner diffs. But I guess for lambdas this happens very rarely anyways. -- https://bugs.ruby-lang.org/