Yurez23

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Apr 3rd, 2023
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  1. • Could not deduce (HasServer layout0)
  2. arising from a type ambiguity check for
  3. the type signature for ‘route’
  4. from the context: HasServer layout
  5. bound by the type signature for:
  6. route :: forall layout.
  7. HasServer layout =>
  8. Server layout -> Request -> Maybe (IO String)
  9. at C:\Users\Iurii\Documents\MEGA\Haskell\Bragilevsky\13\api\Api3.hs:(71,3)-(75,21)
  10. The type variable ‘layout0’ is ambiguous
  11. • In the ambiguity check for ‘route’
  12. To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
  13. When checking the class method:
  14. route :: forall layout.
  15. HasServer layout =>
  16. Server layout -> Request -> Maybe (IO String)
  17. In the class declaration for ‘HasServer’typecheck(-Wdeferred-type-errors)
  18. • Couldn't match type: Server layout0
  19. with: Server layout
  20. Expected: Server layout -> Request -> Maybe (IO String)
  21. Actual: Server layout0 -> Request -> Maybe (IO String)
  22. NB: ‘Server’ is a non-injective type family
  23. The type variable ‘layout0’ is ambiguous
  24. • In the ambiguity check for ‘route’
  25. To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
  26. When checking the class method:
  27. route :: forall layout.
  28. HasServer layout =>
  29. Server layout -> Request -> Maybe (IO String)
  30. In the class declaration for ‘HasServer’typecheck(-Wdeferred-type-errors)
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