On 11.08.2013 12:31, Matthieu Monrocq wrote:
I cannot comment on the difficulty of implementation, however I can
only join Armin in wishing that if it ever takes off it would be
better to make the declaration explicit rather than having to parse
the definition of the function to suddenly realize that this is not a
simple function but a full-blown generator.
As already mentioned in the response to Armin, Rust's requirement for
explicitly declared return types will let you see already in the
functions signature whether you are dealing with an iterator.
However, there is a small (technical) problem with writing a function
signature like this:
fn generate() -> Iterator<int> {...}
since Iterator<T> is just a trait and can't be returned by value
(because its concrete type is not known). We could still allow the
above; but it could lead to some confusion as to why it sometimes is
allowed to return a trait by value and most of the time it's not. A
possible solution for this would be to use some special syntax for
yielding functions, such as:
fn generate() -> yield int {...}
where the 'yield int' part could then be replaced with the concrete
(generated) iterator type by the compiler. This would make it more
explicit that something special is happening here, and it would make the
python people happy at the same time :)
-Michael
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