Created
May 20, 2022 10:03
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example for HasCodec instances for sum types with more than two variants
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| data FooBarBaz = Foo Int String | Bar Bool Text | Baz Bool Bool Bool | |
| instance HasCodec FooBarBaz where | |
| codec = | |
| dimapCodec f g $ | |
| disjointEitherCodec | |
| ( object "Foo" $ | |
| (,) | |
| <$> requiredField' "int" .= fst | |
| <*> requiredField' "string" .= snd | |
| ) | |
| ( disjointEitherCodec | |
| ( object "Bar" $ | |
| (,) | |
| <$> requiredField' "bool" .= fst | |
| <*> requiredField' "text" .= snd | |
| ) | |
| ( object "Baz" $ | |
| (,,) | |
| <$> requiredField' "bool_1" .= (\(b, _, _) -> b) | |
| <*> requiredField' "bool_2" .= (\(_, b, _) -> b) | |
| <*> requiredField' "bool_3" .= (\(_, _, b) -> b) | |
| ) | |
| ) | |
| where | |
| f = \case | |
| Left (i, s) -> Foo i s | |
| Right (Left (b, t)) -> Bar b t | |
| Right (Right (b1, b2, b3)) -> Baz b1 b2 b3 | |
| g = \case | |
| Foo i s -> Left (i, s) | |
| Bar b t -> Right (Left (b, t)) | |
| Baz b1 b2 b3 -> Right (Right (b1, b2, b3)) | |
| data OneTwoThreeFour = One Bool | Two Int | Three Text | Four String | |
| instance HasCodec OneTwoThreeFour where | |
| codec = | |
| dimapCodec f g $ | |
| disjointEitherCodec | |
| ( disjointEitherCodec | |
| (object "one" $ requiredField' "b") | |
| (object "two" $ requiredField' "bool_3") | |
| ) | |
| ( disjointEitherCodec | |
| (object "three" $ requiredField' "text") | |
| (object "four" $ requiredField' "string") | |
| ) | |
| where | |
| f :: Either (Either Bool Int) (Either Text String) -> OneTwoThreeFour | |
| f (Left (Left b)) = One b | |
| f (Left (Right n)) = Two n | |
| f (Right (Left txt)) = Three txt | |
| f (Right (Right s)) = Four s | |
| g :: OneTwoThreeFour -> Either (Either Bool Int) (Either Text String) | |
| g (One b) = Left (Left b) | |
| g (Two n) = Left (Right n) | |
| g (Three txt) = Right (Left txt) | |
| g (Four s) = Right (Right s) |
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