It's not exactly what you are looking for, but I did a blog post about the TRE regex engine which does approximate matching and included links to some other good blog posts: http://ducktape.blot.im/tre-a-regex-engine-with-approximate-...

Also, my favorite library for approx matching, which is heavy duty in some cases, is https://github.com/Martinsos/edlib

Which has python bindings and Nim binding among others.