2 ds051.hs:6: Warning: Pattern match(es) are overlapped in the definition of function `f1':
5 ds051.hs:11: Warning: Pattern match(es) are overlapped in the definition of function `f2':
6 f2 ('a' : ('b' : [])) = ...
8 ds051.hs:16: Warning: Pattern match(es) are overlapped in the definition of function `f3':