Macro impl_altinteger_slice 

macro_rules! impl_altinteger_slice {
    ($ty:ty) => { ... };
}

AltIntegerData for any container that derefs to [i32].

s binds the underlying &[i32] uniformly across Vec / Box<[T]> / &[T] / Cow, sidestepping the self.len() ambiguity between AltrepLen::len and the inherent slice/Vec len.