At the risk of beating the head of a dead horse, and then recursively beating the rest of it, as it sprouts new heads from its tail, I began to think about how a functional programmer would implement shuffle, and no clear solution came to mind. I found a paper that had a binary-tree-based offering (look for "Efficient implementation" in it) that I, as a Haskell illiterate, could make little sense of.

So in the spirit of some of the challenges of late, I challenge our functional programming mavens to offer a Perl functional programming shuffle on a lazy list. You can translate from the Haskell in the paper or present your own solution. The emphasis should be on clarity and elegance (as it always is in functional programming); ideal efficiency appears to be O(N log N) due to lazy lists having no O(1) indexing. O(N^2) is acceptable, I reckon.

Caution: Contents may have been coded under pressure.

In reply to Functional shuffle by Roy Johnson

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