Mark H Weaver <mhw@netris.org> writes:

> Okay, good point.  Indeed, the expansion time of our 'and' and 'or'
> macros is quadratic in the number of operands.  They are implemented in
> boot-9.scm as follows:
>
>   (define-syntax and
>     (syntax-rules ()
>       ((_) #t)
>       ((_ x) x)
>       ((_ x y ...) (if x (and y ...) #f))))
>   
>   (define-syntax or
>     (syntax-rules ()
>       ((_) #f)
>       ((_ x) x)
>       ((_ x y ...) (let ((t x)) (if t t (or y ...))))))
>
> The problem is that the "y ..." pattern has to iterate down the entire
> list to verify that it's a proper list, and this is done for each
> operand.

Why would it have to do that?  It cannot be anything valid else if it is
a pair.

Note that the compiler does not bother to do this for other cases: if I
write