Re: The poor state of documentation of pcase like things.

[Dmitry Gutov]

On 01/03/2016 03:07 AM, Lars Magne Ingebrigtsen wrote:

> The only way you'll know whether `status-symbol' is really a symbol, and
> all the cases are really symbols, is by reading the entire thing.  The
> 44th case could have been (_ foo bar zot), for instance.

How is that different from cond? If I have cond like this:

(cond
 ((eq status-symbol 'unauthorized)
  (url-http-handle-authentication nil))
 ((eq status-symbol 'payment-required)
  (url-mark-buffer-as-dead buffer)
  (error "Somebody wants you to give them money"))
 ...)

...you'll also have to read until its end to find out for sure whether 
the variable name lies or not:

(cond
 ((eq status-symbol 'unauthorized)
  (url-http-handle-authentication nil))
 ((eq status-symbol 'payment-required)
  (url-mark-buffer-as-dead buffer)
  (error "Somebody wants you to give them money"))
 ((memq 'zomg status-symbol)
  (give-away all-moneys)))

> In Common Lisp, you'd say

cl-case is more restricted, yes, but I thought this discussion was about 
how pcase is worse than cond.

> I kinda liked pcase at first, but the more I see of the pcase language,
> the more sceptical I get.  I'm beginning to wonder whether the whole
> thing is a misfeature that should be replaced with several separate
> operators.

You mean pattern matching? A lot of language and library designers would 
disagree with you.