Re: Code for cond*

[Stefan Monnier <monnier@iro.umontreal.ca>]

> > Admittedly, for `cdr-ignore` it would take more than a one-liner,
> > because it affects the interpretation of all the patterns within it
> > (which makes its meaning somewhat unclear: should `(constrain x (null
> > (cdr x)))` be ignored if it appears within a `cdr-ignore`?).
> It affects only the built-in patterns that destructure cons cells
> and lists

That still doesn't clarify its meaning.
E.g. I understand that `(head ,b) should match (head 1 2), but what
about matching a value like (head) ?
The code I have found so far makes it not match (head).
How should this be documented?
Why was this chosen?

The main use-case I can think of for `cdr-ignore` is when matching
against things like Lisp code, where a pattern like

    `(lambda ,args . ,body)

should also match (lambda) because (lambda) is a (broken) lambda
expression rather than being something *else* than a lambda expression.

So I'm not sure the behavior you chose for `cdr-ignore` is the one
we want.


        Stefan