Re: alist and multiple values for one key

[Hannu Koivisto <azure@iki.fi>]

Friedrich Dominicus <frido@q-software-solutions.com> writes:

> This code will work for the given data:
> (defun collect-if (pred list)
>   (mapcar #'(lambda (el) (when (funcall pred el) el)) list))
>
> you can call it with
> (collect-if #'(lambda (item) (eq (car item) 'pine)) trees)
>
> ((pine . cones) (pine . acorns))

I'm afraid that is not what your example expression evaluates to.
Did you try it?  Learn about mapcan if you want to get your code
right using one of the map... functions.  Of course, to return
just the values as requested by the OP you will need other changes
as well.

-- 
Hannu