Ad-hoc Iterator

This is a very small crate providing a macro and a function that allow for conveniently creating iterators on the fly.

The Iterator Trait is very useful. The problem ist just that we can't simply construct an iterator in-place, but rather have to define a struct, impl the Iterator trait for it, and then return a value of that struct.

With the iterate macro of this crate, you can however do exactly that. See it's documentation for more information.

With the iterator_from function, you can directly create an iterator from an FnMut closure (which is exactly the same as what the iterate macro is doing).