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> REBOL/Red-lang goes more towards "a more pragmatic regular language for pattern recognition"

Rebol and Red use embedded PEG parsers, which, by definition, support context-free, and not just regular, languages.

I'm fascinated by PEG parsers, but I don't know whether they can be implemented in a way that's remotely as performant as even mediocre regular expression implementations, much less tuned SIMD extravaganzas.

That would be a stretch goal for me: build a regular expression / automata library that's sufficiently modular to keep some components and drop in more expressive constructs (not necessarily PEGs, but maybe pushdown automata).

Not, sure - but I just came across this in the Nim standard library:

http://nim-lang.github.io/Nim/pegs.html

> Simple PEG (Parsing expression grammar) matching. Uses no memorization, but uses superoperators and symbol inlining to improve performance. Note: Matching performance is hopefully competitive with optimized regular expression engines.

I've written a lot of things that are "hopefully competitive" with something else, but generally benchmarking is the ideal. :-) Hard to benchmark PEG vs regex fairly. Not dismissing it out of hand, as I've had many years to observe the weak spots of regex at quite a short distance.

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