Re: pcase defuns

[Andrew Hyatt]

On Sun, Mar 27, 2022 at 05:31 AM Stefan Monnier 
<monnier@iro.umontreal.ca> wrote: 

> > (defun-pattern fibonacci 
> >    "Compute the fibonacci sequence." 
> >     ((0) 0) ((1) 1) ((n) 
> >       (+ (fibonacci (- n 1)) 
> >            (fibonacci (- n 2))))) 
>
> If you go and benchmark this function, you'll see that its 
> performance sucks even more than the usual naive fibonacci that 
> it appears to be implementing.

Sure, I believe that. If you macroexpand-1 this, you'll see that 
it's implemented with pcase in a pretty straighforward manner, so 
this isn't adding overhead beyond pcase's, I believe. My example 
is about showing how the defun-pattern looks in practice, not 
recommending that using it for computation-intensive functions is 
a particularly good idea.

I see this as trading performance for clarity. Now that you 
mention it, I'll note this in the docstring.
>         Stefan