Re: pcase-dolist

[Stefan Monnier <monnier@iro.umontreal.ca>]

>   (pcase-let ((`(,w ,x ,y ,z) '(1 2 3)))
>     (message "%s %s %s %s" w x y z))

> prints "1 2 3 nil" although the pattern when used in `pcase' wouldn't
> match that list but only 4-element lists.  So a pcase pattern has
> different semantics depending on whether it is used in `pcase' or
> `pcase-let' or `pcase-dolist' which doesn't feel right.

> I'd prefer if `pcase-let' would signal an error if some pattern doesn't
> match.

So you'd want the above to signal an error in the case of:

   (pcase-let ((`(,w ,x) '(1 2 3)))
     (message "%s %s" w x))

?


        Stefan