Grade down - kevinlawler/kona GitHub Wiki

>x (grade-down) is the same as grade-up (<x), except it orders the permutation highest-to-lowest.

  x:0 5 1 3 4 9 7
0 5 1 3 4 9 7
  x[<x]       / x[grade-up x] - sort ascending
0 1 3 4 5 7 9
  x[>x]       / x[grade-down x] - sort descending
9 7 5 4 3 1 0