ExpandSynsFail3.hs:21:8: error: [GHC-83865]
    • Couldn't match type ‘Bool’ with ‘Int’
      Expected: T (T3, T5, Int)
        Actual: T (T5, T3, Bool)
      Type synonyms expanded:
      Expected type: T (T3, T3, Int)
        Actual type: T (T3, T3, Bool)
    • In the first argument of ‘f’, namely
        ‘(undefined :: T (T5, T3, Bool))’
      In the expression: f (undefined :: T (T5, T3, Bool))
      In an equation for ‘a’: a = f (undefined :: T (T5, T3, Bool))