Re: pcase: Semantics of atom QPATS

[Stefan Monnier <monnier@IRO.UMontreal.CA>]

>> Which is why I prefer signaling an error: it lets us extend the
>> semantics of ` without any fear of breaking backward compatibility.
> May I add a comment like this to clarify?

Sure.  Feel free to add support for floats while you're there.


        Stefan


>  lisp/emacs-lisp/pcase.el | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/lisp/emacs-lisp/pcase.el b/lisp/emacs-lisp/pcase.el
> index d3e8899706..32c36ab2cd 100644
> --- a/lisp/emacs-lisp/pcase.el
> +++ b/lisp/emacs-lisp/pcase.el
> @@ -981,6 +981,8 @@ pcase--u1
>            (app car ,(list '\` (car qpat)))
>            (app cdr ,(list '\` (cdr qpat)))))
>     ((or (stringp qpat) (integerp qpat) (symbolp qpat)) `',qpat)
> +   ;; In all other cases just raise an error so we can't break
> +   ;; backward compatibility in the future:
>     (t (error "Unknown QPAT: %S" qpat))))
>  
>  (provide 'pcase)