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1. class (Enum a, Bounded a) => MessageEnum a

   proto-lens	Data.ProtoLens.Message

   A class for protocol buffer enums that enables safe decoding.

2. maybeToEnum :: MessageEnum a => Int -> Maybe a

   proto-lens	Data.ProtoLens.Message

   Convert the given Int to an enum value. Returns Nothing if no corresponding value was defined in the .proto file.

3. readEnum :: MessageEnum a => String -> Maybe a

   proto-lens	Data.ProtoLens.Message

   Convert the given String to an enum value. Returns Nothing if no corresponding value was defined in the .proto file.

4. showEnum :: MessageEnum a => a -> String

   proto-lens	Data.ProtoLens.Message

   Get the name of this enum as defined in the .proto file. Used for the human-readable output in Data.ProtoLens.TextFormat.

5. module Data.ProtoLens.Message.Enum

   This internal module provides functions used to define the various enumFrom* functions of Enum. We expect fromEnum to be an ordering homomorphism, that is:

   forall a b. Enum a b
   succ a == b => fromEnum a < fromEnum b
   

   Note that this homomorphism is most likely not surjective. Note further that one cannot assume:

   CANNOT BE ASSUMED !
   succ a == b => fromEnum a + 1 == fromEnum b
   

   The succ essor of a given message enum value A that's not maxBound is the enum value B whose fromEnum value is the one immediately after A's fromEnum value. That is, fromEnum determines order, but not distance. As an example, consider the enum in the test suite:

   enum Baz {
   BAZ1 = 1; BAZ2 = 2; BAZ3 = 4; BAZ4 = 6;
   BAZ5 = 7; BAZ6 = 9; BAZ7 = 10; BAZ8 = 12;
   }
   

   In this case, succ BAZ2 is BAZ3 despite their fromEnum values differing by 2. Further, [BAZ2, BAZ4 ..] or equivalently messageEnumFromThen BAZ2 BAZ4 is every other enum (i.e. a distance of 2) when taken as a list, i.e. [BAZ2, BAZ4, BAZ6, BAZ8] despite the fromEnum distances being [4, 3, 3]. That said, it is highly unwise to use any of the [a,b ..*] patterns or enumFromThen* functions since adding or removing enums values can cause previously functioning code to fail. I.e. removing BAZ3 in the above example makes the result equivalent fromEnum BAZ2 and the sequence now includes every enum value save BAZ1. This is all despite the fact that BAZ3 was never referenced.

6. messageEnumFrom :: (Enum a, Bounded a) => a -> [a]

   proto-lens	Data.ProtoLens.Message.Enum

   No documentation available.

7. messageEnumFromThen :: (Enum a, Bounded a) => a -> a -> [a]

   proto-lens	Data.ProtoLens.Message.Enum

   No documentation available.

8. messageEnumFromThenTo :: Enum a => a -> a -> a -> [a]

   proto-lens	Data.ProtoLens.Message.Enum

   No documentation available.

9. messageEnumFromTo :: Enum a => a -> a -> [a]

   proto-lens	Data.ProtoLens.Message.Enum

   No documentation available.

10. class Enum a

    protolude	Protolude

    Class Enum defines operations on sequentially ordered types. The enumFrom... methods are used in Haskell's translation of arithmetic sequences. Instances of Enum may be derived for any enumeration type (types whose constructors have no fields). The nullary constructors are assumed to be numbered left-to-right by fromEnum from 0 through n-1. See Chapter 10 of the Haskell Report for more details. For any type that is an instance of class Bounded as well as Enum, the following should hold:

    • The calls succ maxBound and pred minBound should result in a runtime error.
    • fromEnum and toEnum should give a runtime error if the result value is not representable in the result type. For example, toEnum 7 :: Bool is an error.
    • enumFrom and enumFromThen should be defined with an implicit bound, thus:

    enumFrom     x   = enumFromTo     x maxBound
    enumFromThen x y = enumFromThenTo x y bound
    where
    bound | fromEnum y >= fromEnum x = maxBound
    | otherwise                = minBound
    

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