Design a syntax for an alternative to classic regex. You can also share interesting existing solutions. An example of a regular expression to try implementing is the JSON number spec:
n = /-?(?:0|[1-9]\d*)(?:\.\d+)?(?:[eE][+-]?\d+)?/
All the examples here are licensed CC0. If you would like to share a solution for addition to this gist (and later a repository), send it to me and mention that you license it under CC0. If you would like to be attributed, mention under what name.