2 ds020.hs:5: Warning: Pattern match(es) are overlapped
3 In the definition of `a': a ~(~[], ~[], ~[]) = ...
5 ds020.hs:8: Warning: Pattern match(es) are overlapped
6 In the definition of `b': b ~(~x : (~xs : ~ys)) = ...
8 ds020.hs:13: Warning: Pattern match(es) are overlapped
9 In the definition of `d':
13 ds020.hs:19: Warning: Pattern match(es) are overlapped
14 In the definition of `f': f (x@~[]) = ...