Enumeration Hooks

The Binding Generator C->Haskell : Implementation of Haskell Binding Modules : Enumeration Hooks
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## 2.5. Enumeration Hooks

> `{#enum cid [as hsid] {alias1 , ... , aliasn} [with prefix = pref] [deriving (clid1 , ... , clidn)]#}`

Rewrite the C enumeration called cid into a Haskell data type declaration, which is made an instance of `Enum` such that the ordinals match those of the enumeration values in C. This takes explicit enumeration values in the C definitions into account. If hsid is given, this is the name of the Haskell data type. The identifiers clid1 to clidn are added to the deriving clause of the Haskell type.

By default, the names of the C enumeration are used for the constructors in Haskell. If alias1 is `underscoreToCase`, the original C names are capitalised and the use of underscores is rewritten to caps. If it is `upcaseFirstLetter` or `downcaseFirstLetter`, the first letter of the original C name changes case correspondingly. It is also possible to combine `underscoreToCase` with one of `upcaseFirstLetter` or `downcaseFirstLetter`. Moreover, alias1 to aliasn may be aliases of the form cid `as` hsid, which map individual C names to Haskell names. Instead of the global prefix introduced by a context hook, a local prefix pref can optionally be specified.

As an example, consider

> `{#enum WindowType {underscoreToCase} deriving (Eq)#}`

Note: The `enum define` hooks described in the C->Haskell paper are not implemented yet.

The Binding Generator C->Haskell : Implementation of Haskell Binding Modules : Enumeration Hooks
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