T20642.hs:10:3: warning: [-Wincomplete-uni-patterns (in -Wall)]
    Pattern match(es) are non-exhaustive
    In a pattern binding:
        Patterns of type ‘([a], [a])’ not matched: (_, [])

T20642.hs:14:7: warning: [-Wincomplete-patterns (in -Wextra)]
    Pattern match(es) are non-exhaustive
    In a case alternative:
        Patterns of type ‘Maybe a’ not matched:
            Nothing
            Just _

T20642.hs:18:1: warning: [-Wincomplete-patterns (in -Wextra)]
    Pattern match(es) are non-exhaustive
    In an equation for ‘g’:
        Patterns of type ‘(Bool, [a])’ not matched: (_, (_:_))