• Simon Peyton Jones's avatar
    Fix Trac #5892: a coding errors · 3e00d046
    Simon Peyton Jones authored
    We had a lazy pattern
      gres@(gre:_) = blah
    and then a test for (null gres).  But I'd forgotten
    that a demand for *any* of variables in the pattern
    matches *all* of the variables in the entire pattern.
    So the test for (null gres) was matching the cons,
    which defeats the purpose.
RnPat.lhs 24.3 KB