- leaning toothpick syndrome: what do I have to escape? How many times? https://www.xkcd.com/1638/
- subtle differences but similar syntax between languages
- Cognitive load: I am not excited about learning which characters are metacharacters and when. See e.g. http://www.greenend.org.uk/rjk/tech/regexp.html.
- not really programmable. To decompose a POSIX-expressed regex into its constituent parts would require a nontrivial function.
- Scheme’s irregex
- Common Lisp: CL-PPCRE’s S-expression syntax
- elisp-regex-dsl for Emacs lisp
- https://verbalexpressions.github.io/ for many languages, including Clojure
- Perl 6 rules. Note the use of
beforeinstead of metacharacters
?=. Also, to be clear, these rules can be much more powerful/expressive than regular expressions. This could be regarded as a bug or a feature.