Function rdx::util::partition

pub fn partition<T, P>(a: &mut [T], p: P) -> usize where
    P: Fn(&T) -> bool, 

Partition an array such that all elements for which p returns true are placed before all elements for which p returns false. The order other than this is undefined. Return the index of the first element for which p returns false, or the length of the array if p is true for all elements.