T5331.hs:8:17: Warning:
    Unused quantified type variable ‛a’
    In the definition of data constructor ‛S1’

T5331.hs:11:16: Warning:
    Unused quantified type variable ‛a’
    In the definition of data constructor ‛W1’

T5331.hs:13:13: Warning:
    Unused quantified type variable ‛a’
    In the type ‛forall a. Int’
    In the type signature for ‛f’