[plt-scheme] Names in signatures

From: Jens Axel Søgaard (jensaxel at soegaard.net)
Date: Wed Jun 4 12:11:16 EDT 2003

Robby Findler wrote:
 > Jens Axel Søgaard:

> > (define-signature catenable-double-ended-list^
> >  ((open double-ended-list)
> >    (open catenable-list)))
> > The last signature is giving me problems. The syntax checker
> > says that some names are defined multple times, and that's
> > true. But in this case it on purpose.
> > NB: I am sitting on a computer without Scheme, so the
> > above is not syntax-checked.

> Yeah, you just cannot do that. You'd have to write something like this:
> (define-signature catenable-list-extensions^
>   (append))
> (define-signature catenable-list^
>   ((open list^)
>    (open catenable-list-extensions^)))
Thanks, that works. It just feels akward.

Is there a technical reason not to the union of the sets of imported names
from the opened signatures (such as the signatures need to be a DAG).

For those cases where the clash is not intentional it is a good thing to
get an error here though.

Jens Axel Søgaard

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