Re: combining cond and let, to replace pcase.

[Dmitry Gutov]

On 19/11/2023 15:08, Eli Zaretskii wrote:
> > Actually both and none, this is exactly the point I raised in my other
> > reply - both have exactly the same complexity, and it is totally
> > subjective and only habit which one you prefer.
> It isn't only that.  It is also that the obscure and subtle nature of
> regexp strings makes it easy to make mistakes.  Just look at the sheer
> number of regexp mistakes uncovered in our code base by Mattias
> Engdegård during the last year.  It isn't an accident.

pcase is much better guarded against programmer mistakes because in a 
lot of cases typos or misunderstandings will be highlighted by the 
byte-compiler (potentially, with flymake directly in the buffer, which I 
also recommend everyone to enable).

Both rx and string regexps aren't able to take advantage of such. 
Mattias's checker took a lot of steps toward the same functionality, but 
it's ultimately limited, e.g. because we don't annotate regexps any 
differently from strings in the code.