DB<17> sub tst { say "@_" }


  DB<18> $i=0;tst $i,$i,++$i          # last increment operates on first two aliases       
1 1 1


  DB<19> $i=0;tst $i,$i,$i++          # again, increment returns value at evaluation time
1 1 0


  DB<20> $i=0;tst $i++,$i,$i++        # increments return value, but influence alias in the middle
0 2 1

##</code><code>##

        $i = $i ++;
        print ++ $i + $i ++;

##</code><code>##

>perl -wE "$i=1; say for $i..$i++"           # 2 .. 1  (first is alias, postinc returns 1 )

>perl -wE "$i=1; say for $i..++$i"           # 2 .. 2  (first is alias, preinc returns 2 )
2
...