Does Rust support using an infix operator as a function?

Question

I am writing a function that does piecewise multiplication of two arrays.

    xs.iter()
        .zip(ys).map(|(x, y)| x * y)
        .sum()

In some other languages, I can pass (*) as a function to map. Does Rust have this feature?

Answer 1

Nnnyes. Sorta kinda not really.

You can't write an operator as a name. But most operators are backed by traits, and you can write the name of those, so a * b is effectively Mul::mul(a, b), and you can pass Mul::mul as a function pointer.

But that doesn't help in this case because Iterator::map is expecting a FnMut((A, B)) -> C, and the binary operators all implement FnMut(A, B) -> C.

Now, you could write an adapter for this, but you'd need one for every combination of arity and mutability. And you'd have to eat a heap allocation and indirection or require a nightly compiler.

Or, you could write your own version of Iterator::map on an extension trait that accepts higher arity functions for iterators of tuples... again, one for each arity...

Honestly, it's simpler to just use a closure.