It wouldn't require any changes to the language. It would probably require a tree-walking macro, which are not too uncommon. You'd want a different name though

It wouldn't require any changes to the language. It would probably require a tree-walking macro, which are not too uncommon. You'd want a different name though since `block` is already a thing in CL. http://clhs.lisp.se/Body/s_block.htm http://clhs.lisp.se/Body/s_block.htm I'd recommend On Lisp by Paul Graham and Let Over Lambda by Doug Hoyt if you're interested in trying it.