2 ms·

Something like Perl6 grammars[1], or maybe Rosie Pattern Language[2]? Of course Perl6 regexes also go well beyond regular expressions, and I suspect they could

by zokier 7y ago

Something like Perl6 grammars[1], or maybe Rosie Pattern Language[2]? Of course Perl6 regexes also go well beyond regular expressions, and I suspect they could be used to match context-free grammars if pressed hard enough. Both P6 grammars and RPL are based on parsing expression grammars, and there are also tools/libraries for many other languages based on PEGs. But now you are entering in the scary realm of parsers and parser generators and all that jazz, and can debate how easy to use they really are. [1] https://docs.perl6.org/language/grammars https://docs.perl6.org/language/grammars [2] https://developer.ibm.com/open/projects/rosie-pattern-language/ https://developer.ibm.com/open/projects/rosie-pattern-langua...

wahern 7y ago
PEGs are amazing precisely because they're as easy to use as, if not easier than, common regular expression syntax. PEGs are literally the same as regular expressions except 1) alternations are ordered, 2) zero-width assertions are formalized, and 3) quantifiers match greedily. This is effectively the same behavior as the Perl-compatible regular expressions with which most people are familiar. Many PEG engines, especially for dynamic languages, permit grammar composition using first-class variables. That might be a small barrier to people more familiar with the terseness and conceptual simplicity of regular expressions as string'ish values. But it's fairly trivial to implement the latter using PEGs. For example, LPeg provides a small auxiliary module for doing that: http://www.inf.puc-rio.br/~roberto/lpeg/re.html http://www.inf.puc-rio.br/~roberto/lpeg/re.html Also, Rosie seems amazing. I've not yet had the opportunity to make use of it, but I attended a presentation of Rosie by the author at a Lua workshop which left me very impressed.

2 ms·

Something like Perl6 grammars[1], or maybe Rosie Pattern Language[2]? Of course Perl6 regexes also go well beyond regular expressions, and I suspect they could

by zokier 7y ago

wahern 7y ago
PEGs are amazing precisely because they're as easy to use as, if not easier than, common regular expression syntax. PEGs are literally the same as regular expressions except 1) alternations are ordered, 2) zero-width assertions are formalized, and 3) quantifiers match greedily. This is effectively the same behavior as the Perl-compatible regular expressions with which most people are familiar. Many PEG engines, especially for dynamic languages, permit grammar composition using first-class variables. That might be a small barrier to people more familiar with the terseness and conceptual simplicity of regular expressions as string'ish values. But it's fairly trivial to implement the latter using PEGs. For example, LPeg provides a small auxiliary module for doing that: http://www.inf.puc-rio.br/~roberto/lpeg/re.html http://www.inf.puc-rio.br/~roberto/lpeg/re.html Also, Rosie seems amazing. I've not yet had the opportunity to make use of it, but I attended a presentation of Rosie by the author at a Lua workshop which left me very impressed.