[Scheme-reports] multiple values module Andy Wingo (19 May 2011 19:36 UTC)
Re: [Scheme-reports] multiple values module John Cowan (19 May 2011 22:10 UTC)

Re: [Scheme-reports] multiple values module John Cowan 19 May 2011 22:10 UTC

Andy Wingo scripsit:

> What's the rationale for breaking call-with-values and values out to
> their own module?

Primarily because they aren't in IEEE/R4RS.

> Suggestion: since it is trivial to implement `call-with-values' with
> a define-record-type <values>, simply require it in the base Scheme.
> If someone is so resource constrained that they cannot include it in
> their system, they can still call their system Scheme, just with a
> small caveat.

There is already a ticket to do this, not for the given reason but
because the Riastradh division operators return two values, unlike any
other standard procedures.

Chibi actually implements multiple purely in Scheme by returning a list
with a unique CAR, which prints as "(value)".

--
John Cowan      <cowan@ccil.org>       http://www.ccil.org/~cowan
                Charles li reis, nostre emperesdre magnes,
                Set anz totz pleinz ad ested in Espagnes.

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