my \A = now; say fib-s 1000; my \B = now; say fib-m 1000; my \C = now; say "sub: {B - A} vs macro: {C - B}"; sub fib-s (\n) { (0, 1, * + * ... Inf)[n] } use experimental :macros; macro fib-m (\n) { {{{ fib-s n }}} }