tcfail102.hs:1:14: warning: [-Wdeprecated-flags (in -Wdefault)]
    -XDatatypeContexts is deprecated: It was widely considered a misfeature, and has been removed from the Haskell language.

tcfail102.hs:9:7: error: [GHC-39999]
    • Could not deduce ‘Integral (Ratio a)’
      from the context: Integral a
        bound by the type signature for:
                   f :: forall a. Integral a => P (Ratio a) -> P (Ratio a)
        at tcfail102.hs:8:1-45
    • In a record update at field ‘p’,
      with type constructor ‘P’
      and data constructor ‘P’.
      In the expression: x {p = p x}
      In an equation for ‘f’: f x = x {p = p x}