On Mon 29 Jun 2009 23:44, Neil Jerram <n...@ossau.uklinux.net> writes:
> Andy Wingo <wi...@pobox.com> writes:
>
>> scheme@(guile-user)> (if %nil 1 2)
>> 1
>>
>> #define scm_is_false(x) (scm_is_eq ((x), SCM_BOOL_F) || SCM_NILP (x))
> Seems wrong to me. In Scheme #f should be the only false value.
> What's the argument for %nil being false in Scheme code?
I thought the original plan regarding %nil and #f and '() was that %nil
wasn't supposed to be seen normally from Scheme, and for that reason
(and (null? %nil) (not %nil)) would not be a problem.
Guile has treated %nil as false for quite some time:
scheme@(guile-user)> ,o interp #t
scheme@(guile-user)> (if %nil 1 2)
$1 = 2
Andy
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