Issue #19107 has been updated by Earlopain (Earlopain _). `->(...) {}` is syntax invalid, same as `foo do |...|; end`, in that regard they are more like blocks. Lambdas do check arity though, which is probably what you were talking about. I'll make a separate issue for this to understand what the desired behavior should be if that's ok. ---------------------------------------- Feature #19107: Allow trailing comma in method signature https://bugs.ruby-lang.org/issues/19107#change-116407 * Author: byroot (Jean Boussier) * Status: Open * Assignee: prism ---------------------------------------- A popular style for multiline arrays, hashes or method calls, is to use trailing commas: ```ruby array = [ 1, 2, 3, ] hash = { foo: 1, bar: 2, baz: 3, } Some.method( 1, 2, foo: 3, ) ``` The main reason to do this is to avoid unnecessary noise when adding one extra element: ```diff diff --git a/foo.rb b/foo.rb index b2689a7e4f..ddb7dc3552 100644 --- a/foo.rb +++ b/foo.rb @@ -1,4 +1,5 @@ Foo.bar( foo: 1, - bar: 2 + bar: 2, + baz: 3 ) ``` However, this pattern doesn't work with method declarations: ```ruby def foo(bar:,) # syntax error, unexpected ')' ``` ### Proposal For consistency and convenience I propose to allow trailing commas in method declarations. -- https://bugs.ruby-lang.org/