s iir ejkucsath  alnroetph eri;
unobfu: s//r ejkucsath  alnroetph er/;

Using i as a delimiter, you substitute nothing with the string "r ejkucsath alnroetph er" (BTW, this only works if you put a space between the s (or q, qq, etc) and the delimiter), thus putting the string in $_;

split$+

This splits the string in $_ on the value of $+ (Last Paren Match), which is undef. So we end up with the array @_ containing each letter of the string in $_ as an element.

print$_[$-++]until($-++>$#_);

This prints every other element of @_, starting with 0 (i.e. 0,2,4,6,8..). $- (default 0) is used as an array index, but it is incremented twice: One time in the until-test, and one time in the array-indexing itself. The printing stops when $- is greater then the number of elements in @_ ($#_)

print$_[$---]until($---<1);

Basically the same as the last line, only in the other direction. $- now points to the last element of @_. $- gets decremented twice, so now all odd numbers are printed (.. 7,5,3,1) until $- is smaller then 1.

And that's it.

One small comment on the last command: This works, too, and is shorter:

print$_[$---]while($---);

But in fact I like the symmetry more...

--
#!/usr/bin/perl
for(ref bless{},just'another'perl'hacker){s-:+-$"-g&&print$_.$/}
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