Re: Checking conditions unrelated to expression

[Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

> Suppose I want to test (eq duck 'quack), cannot use a pcase because tests
> are dependent upon featr.
>
>   (pcase featr
>      ('this (do-this))
>      ('that (do-that))
>      (_ (message "some message"))

Like Thibaut said, for this example `cond` would probably work best.
But if you have good reasons to use `pcase`, you *can* do what
you suggest.
E.g.:

   (pcase featr
      ('this (do-this))
      ('that (do-that))
      (_ (if (eq duck 'quack) (do-not) (message "some message"))))

or

   (pcase featr
      ('this (do-this))
      ('that (do-that))
      ((guard (eq duck 'quack)) (do-not))
      (_ (message "some message")))

or

   (pcase featr
      ('this (do-this))
      ('that (do-that))
      ((let 'quack duck) (do-not))
      (_ (message "some message")))

...


        Stefan