Idiomatic Rust way of making a slice of contiguous integers?

I have an API which wants &[T] to represent a slice of things to sort.

I am indirectly sorting the indices for the actual data, so just want a &[usize] containing 0..len as the starting values.

Weirdly (to me at least) I could not achieve this with any shorthand syntax like:

• (0..len) – Type mismatch [E0308] expected &[usize], but found Range<usize>
• &(0..len) – expected &[usize], found &Range<usize>
• [0..len] – Type mismatch [E0308] expected &[usize], but found [Range<usize>; 1]
• &*[0..len] – error[E0614]: type [std::ops::Range<usize>; 1] cannot be dereferenced
• &[0..len] – ^ expected &usize, found &Range<usize>

The best I could come up with was: &Vec::from_iter(0..len).as_slice() but is this really the neatest/most idiomatic way to achieve this? Could there not be a functional slice which achieves this without an allocation?

>Solution :

This is pretty close to the most idiomatic way to express this, yes. If the context clearly wants a slice then you can shorten it to &Vec::from_iter(0..len) since Vec auto-derefs to a slice.

Otherwise, the other idiomatic way I can think of to express this would be &(0..len).collect::<Vec<_>>() which is slightly longer and requires the ugly turbofish to specify the collection type.