Re: cheap-list

[Freeman Gilmore]

Aaron, thank you; but i do not have a clue.   Were can I read about
this?   Google is no help.
ƒg

On Wed, May 6, 2020 at 10:59 PM Aaron Hill <address@hidden> wrote:
>
> On 2020-05-06 7:34 pm, Freeman Gilmore wrote:
> > What is a  cheap-list  and where is it explained?
> > Thank you, ƒg
>
> There is no such thing as a "cheap list" per se.  cheap-list? is simply
> a faster predicate compared to the standard list?:
>
> ;;;; from c++.scm
> (define-public (cheap-list? x)
>    (or (pair? x) (null? x)))
> ;;;;
>
> All lists will pass cheap-list?, but not all things that pass
> cheap-list? are lists.  Additional care must be taken within the
> function body when using cheap-list? as a type predicate.
>
>
> -- Aaron Hill
>