T10615.hs:5:7: error:
    • Found type wildcard ‘_’ standing for ‘w1’
      Where: ‘w1’ is an ambiguous type variable
      To use the inferred type, enable PartialTypeSignatures
    • In the type ‘_ -> f’
      In the type signature: f1 :: _ -> f

T10615.hs:6:6: error:
    • Couldn't match type ‘f’ with ‘b1 -> w1’
      Expected: w1 -> f
        Actual: w1 -> b1 -> w1
      ‘f’ is a rigid type variable bound by
        the inferred type of f1 :: w1 -> f
        at T10615.hs:5:1-12
    • In the expression: const
      In an equation for ‘f1’: f1 = const
    • Relevant bindings include f1 :: w1 -> f (bound at T10615.hs:6:1)

T10615.hs:8:7: error:
    • Found type wildcard ‘_’ standing for ‘w0’
      Where: ‘w0’ is an ambiguous type variable
      To use the inferred type, enable PartialTypeSignatures
    • In the type ‘_ -> _f’
      In the type signature: f2 :: _ -> _f

T10615.hs:9:6: error:
    • Couldn't match type ‘_f’ with ‘b0 -> w0’
      Expected: w0 -> _f
        Actual: w0 -> b0 -> w0
      ‘_f’ is a rigid type variable bound by
        the inferred type of f2 :: w0 -> _f
        at T10615.hs:8:1-13
    • In the expression: const
      In an equation for ‘f2’: f2 = const
    • Relevant bindings include f2 :: w0 -> _f (bound at T10615.hs:9:1)