pon., 27 sie 2018 o 10:17 <to...@tuxteam.de> napisał(a): > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On Mon, Aug 27, 2018 at 02:17:06AM +0200, Panicz Maciej Godek wrote: > > niedz., 26 sie 2018 o 16:09 HiPhish <hiph...@posteo.de> 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. >
If that's the case, then perhaps actually returning no value (as in the (values) form with no arguments) is the way to go?
