I really like this. One big benefit of this notation, that I feel is under-highlighted in both this comment page and the Rulex site, is that there are no backsl

I really like this. One big benefit of this notation, that I feel is under-highlighted in both this comment page and the Rulex site, is that there are no backslashes in Rulex. A lot of regex usage is inside strings inside another programming language, which typically means double backslash escape messes such as \\\\" and it's just a mess. This makes regexes particularly beginner-unfriendly, because you gotta parse it out at different levels. No backslashes means that you can put a Rulex expression in a string in just about any language, not escape anything, and still get a predictable result. I suspect that a lot of its design actually follows from that requirement. Eg having to quote all character literals/sequences - that's needed because that way, eg a newline can just be "[n]", even inside a character class. (eg ['a'-'z' n]). Also, it looks like you can choose to use either single-quotes or double-quotes. This means that if you use the one style of quotes in your language, you can use the other one in the Rulex expression and still not have to backslash-escape anything.