*beeep* Wrong answer, sorry. You are converting \021 to \036 in the endeffect, and that is not what I'd have expected. Sure, you could change the \040 in the first line to a \042 to fix that but what if there is a character lower than \023 in the original string?

So, taking this, it seems that the following might be the solution:

tr/\017\020\021\022\002-\200/\012\015\040\011\000-\176/;
[download]

For with a quick test it seems that tr takes the first occurence of a character and doesn't care if there is another one later. Is that right, is that maybe even documented on it so I can be sure when using it?
--
use signature; signature(" So long\nAlfie");