Radix sorts actually can be used with many custom comparisons by using a sort by api which is enough to let you express many of the uses of custom sorting (e.g.

Radix sorts actually can be used with many custom comparisons by using a sort by api which is enough to let you express many of the uses of custom sorting (e.g. sorting objects by fields, sorting by absolute value, etc). Given the overhead of radix sorts, it wouldn't shock me if this was faster for small sizes.