Here's a version of the Perl 6 code that's almost as terse as average Haskell code:

my $cmp = sub ($x) {
    state $prv;
    $x ne $prv ?? $prv = $x !! return;
}

[download]

In reply to Re^4: 99 Problems in Perl6 by chromatic
in thread 99 Problems in Perl6 by Ovid

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