I didn't find any specific name for it. I think it's just a part of atom syntax, like " is part of string syntax. But it could also be a reader macro - in Commo

I didn't find any specific name for it. I think it's just a part of atom syntax, like " is part of string syntax. But it could also be a reader macro - in Common Lisp you can override parts of a parsing process. You can write similar macros yourself. For example, Common Lisp doesn't have a dict object literal ({} in json), but as you can see here: https://gist.github.com/chaitanyagupta/9324402 https://gist.github.com/chaitanyagupta/9324402 you can add it.