13:24 >perl -wE "$|++; say ''; sub f { print qq($_[0] ); if ($_[0] >= 99) { say 'Bye!'; } else { f($_[0] + 1); } } f(1);" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 Bye! 13:24 >perl -wE "$|++; say ''; sub f { print qq($_[0] ); if ($_[0] >= 100) { say 'Bye!'; } else { f($_[0] + 1); } } f(1);" 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 Deep recursion on subroutine "main::f" at -e line 1. 100 Bye! 13:24 >perl -v This is perl 5, version 22, subversion 0 (v5.22.0) built for MSWin32-x64-multi-thread