Alex Shinn <alexsh...@gmail.com> writes:
>> Of course, it is not hard to work around these seemingly pointless
>> prohibitions, just as it would not be hard to write
>>
>> (if (null? xs) 0 (apply + xs))
>>
>> instead of
>>
>> (apply + xs)
>>
>> but I don't understand why we should have to. What's the compelling
>> argument on the other side that justifies these annoyances?
>
> This analogy is meaningless, but for the record
> you should be using fold or reduce here.
Yes, I'm aware that using `fold' or `reduce' is more robust for large
lists. You could just as easily correct anyone who uses alists in a
simple example and say "for the record you should be using a balanced
tree instead."
Or perhaps you're advocating (reduce + 0 xs) over (apply + xs) as a
matter of style. If so, I happen to agree with you, but that's not the
point. The point is, (apply + xs) is a sensible thing for someone to do
if xs is not huge, and it's good that Scheme treats this degenerate case
properly.
Similarly, if we are generating a sequence of expressions to be
evaluated for effects only, then an empty sequence has a perfectly
logical and obvious meaning.
Thanks,
Mark
