That says:
| The macros described in this section use ‘pcase’ patterns
to perform
| destructuring binding. The condition of the object to be of
compatible
| structure means that the object must match the pattern,
because only
| then the object’s subfields can be extracted. For example:
|
| (pcase-let ((`(add ,x ,y) my-list))
| (message "Contains %S and %S" x y))
|
| does the same as the previous example, except that it directly
tries to
| extract ‘x’ and ‘y’ from ‘my-list’ without first verifying if
‘my-list’
| is a list which has the right number of elements and has ‘add’
as its
| first element. The precise behavior when the object does not
actually
| match the pattern is undefined, although the body will not be
silently
| skipped: either an error is signaled or the body is run with
some of the
| variables potentially bound to arbitrary values like ‘nil’.
That explains the same thing quite broadly. Maybe you did not
notice
the implications when you first read it? I dunno, I'm not that
good in
writing documentation, but I can't find something to add from
what we
had discussed that would not be redundant.