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0 pointsburntsushi2y ago0 comments

I've never used cl-ppcre myself, but its docs[1] claim that it provides compile-time regexes:

> CL-PPCRE uses compiler macros to pre-compile scanners at load time if possible. This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time and is intended to save the time for creating scanners at execution time (probably creating the same scanner over and over in a loop).

[1]: https://edicl.github.io/cl-ppcre/

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foota2y ago

I think this is more like caching the regex than creating it at compile time? Load time I think is basically runtime. I think lisp can be loaded and then rehydrated later, but I'm not sure how common that is.

burntsushiOP2y ago

Hard to say exactly since I don't have experience with cl-ppcre, but this line seems to suggest something is actually happening at complile time:

> This happens if the compiler can determine that the regular expression (no matter if it's a string or an S-expression) is constant at compile time

If this were just a run of the mill caching mechanism, then whether the pattern was a constant at compile time wouldn't matter.

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