You're going to have to try harder if you want Haskell to outgolf Perl 6 here. The following all work in Pugs and are shorter than your Haskell version. 
    sub reverseWords ($_) {~reverse .comb}
    sub reverseWords {~reverse comb @_}
    my&reverseWords:={~.comb.reverse}

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The first two could even be construed as readable.

In reply to Re: Five Ways to Reverse a String of Words (C#, Perl 5, Perl6, Ruby, Haskell) by TimToady
in thread Five Ways to Reverse a String of Words (C#, Perl 5, Perl 6, Ruby, Haskell) by eyepopslikeamosquito

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