Ben Jones: > auto sorter = (Tuple x, Tuple y) => x.get(0) < y.get(0); > sort!sorter(zip(a,b)); You can write that as (untested): zip(a, b).sort!((x, y) => x[0] < y[0]); Or even just: a.zip(b).sort!q{ a[0] < b[0] }; Bye, bearophile