Re: Replace trivial pcase occurrences in the Emacs sources

[Clément Pit-Claudel]

On 30/10/2018 14.14, Alan Mackenzie wrote:
> Hello, Clément.

Hey Alan :)

> On Tue, Oct 30, 2018 at 11:05:55 -0400, Clément Pit-Claudel wrote:
>> On 30/10/2018 10.16, Andy Moreton wrote:
>>> How are users meant to write reliable code using such constructs ?
> 
>> Ensure that the pattern actually matches :)
> 
> You mean, unless you can be 100% sure that the pattern will match, you
> mustn't use pcase-... constructs.  That sounds equivalent to saying you
> shouldn't use these constructs at all.

That's an odd conclusion.

>> IOW, only use these constructs when it's an invariant of your program
>> that the pattern will match the data.  For cases in which the pattern
>> might not match, use pcase instead of pcase-dolist.
> 
> pcase is not a looping construct.  pcase-dolist is.  They're not
> replacements for eachother.

I should have written "use `pcase' with `dolist` instead of `pcase-dolist'".  
Concretely, replace this:

(pcase-dolist (pat list) …) 

with this: 

(dolist (xyz list) (pcase xyz (pat …) (_ (handle-error-here))))