The use case for this would be that it doesn't reify the block IOW doesn't allocate a proc to wrap the block. ... but that optimisation has already been made†

The use case for this would be that it doesn't reify the block IOW doesn't allocate a proc to wrap the block. ... but that optimisation has already been made† (and IIRC it is too for *args and **kwargs that just get forwarded to calls), so it mostly exists for consistency with anonymous * and ** and valueless keys, as well as documentation (making it explicit that the method accepts a block right from the signature). Here's the discussion: https://bugs.ruby-lang.org/issues/11256 https://bugs.ruby-lang.org/issues/11256 I don't particularly like it given the style I like to use, but I can see how people using a certain different style would as their style would be more consistent and carry better intent. Anyway the post linked from the OP has a more detailed rundown: https://zverok.space/blog/2023-11-24-syntax-sugar4-argument-forwarding.html https://zverok.space/blog/2023-11-24-syntax-sugar4-argument-... † https://bugs.ruby-lang.org/issues/14045 https://bugs.ruby-lang.org/issues/14045