Re: A value for "nothing"

[tomas]

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On Mon, Aug 27, 2018 at 02:17:06AM +0200, Panicz Maciej Godek wrote:
> niedz., 26 sie 2018 o 16:09 HiPhish <address@hidden> napisał(a):
> 
> > Hello Schemers,
> >
> > I am writing an implementation of MessagePack [1] for Guile and a part of
> > the
> > spec is the presence of a "nil" data type. What would be a good value to
> > express "nothing" in Guile? I cannot use '() because that would be
> > indistinguishable from the empty list, so I thought that the return value
> > of a
> > function that returns nothing would be a good fit. The function `display`
> > for
> > example returns an `#<unspecified>` value, but the only way of producing
> > it
> > without side effects so for is the value of `(if #f #f)`. Is there a
> > better
> > way?
> >
> >
> In my experience, if #f doesn't make sense as a legal value, then using #f
> is probably the idiomatic Scheme way to go.

[...]

In this case, as msgpack has explicit true and false values, those seem
the "natural" correspondents of Scheme's #t and #f.

Cheers
- -- tomás
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