I've always wanted to see an implementation of Inline::Haskell (a la Inline::C). And I figured functions could return references to tied file handles to take care of (possibly infinite) lazy lists.

$fh=haskell_func();
while(<$fh>)
{
    ...etc...
}
@foo=map $_*2, <$fh>;

__HASKELL__
haskell_func = primes [2..]
        where
         primes [x:xs] = x:primes (filter (\n->(mod n x)/=0) xs)
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