You have to be careful with any state solution. They'll work fine until you go through the same code path again (due to a loop, the sub it's in called again, etc). Being a state variable, it'll retain whatever was in it last. So you have to be careful you aren't comparing the last element of the first list with the first element of the second list. 
@cleaned = @uncleaned[0, grep {@uncleaned[$i] ne @uncleaned[$i-1]} 1..
+$#uncleaded];

[download]
It needs some additional hackery to deal with undefs correctly.

In reply to Re: reduce like iterators by JavaFan
in thread reduce like iterators by LanX

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