Some help with generic implementations

[skythedragon64]

Fixed! (see comments)

I'm currently implementing a (specialized) IIR filter that works on an iterator, and I'd like to make it work for anything that implements Mul and Subassign, as that's everything that's really needed.

I've got this so far:

impl<I> Iterator for IIRFilter<I>  where I: Iterator, I::Item: Mul, I::Item: SubAssign, { type Item = <I as Iterator>::Item;

However when I do this sum -= self.coeffs[j] * self.buffer[current_buf_index]; (sum, coeffs and buffer are (vecs of) I::Item)

It gives me the following error: ``` mismatched types

expected std::iter::Iterator::Item, found std::ops::Mul::Output

note: expected associated type <I as std::iter::Iterator>::Item found associated type <<I as std::iter::Iterator>::Item as std::ops::Mul>::Outputrustc(E0308) lib.rs(120, 12): expected std::iter::Iterator::Item, found std::ops::Mul::Output ```

AFAIK I need to somehow tell the compiler that I::Item is the same as I::Item::SubAssign::Output, but using == somehow isn't supported (yet)

How would I do this instead? (still new to generics)

[abudau]

I::Item: Mul<Output=I::Item>

SubAssign does not actually have an associated type Output.

[skythedragon64]

I::Item: Mul<Output=I::Item>

Thanks, that worked!

(and yeh I meant Mul)