Pretty Printer for textual version of Language (name) in DynFlags

I feel that the GHC API could benefit from a Show instance for Language in DynFlags.hs.

Currently, if we want to display the language being used we have to do something like

          foo inf = case hmi_language inf of
            Nothing -> Nothing
            Just Haskell98 -> Just "Haskell98"
            Just Haskell2010 -> Just "Haskell2010"

This is pretty much just the Show instance (over Maybe) and Haskell can derive it for us automatically: we just need to change deriving Enum to deriving (Enum, Show). The above solution is not the most robust ever as if this data type is ever changed, this starts to form an incomplete pattern. If we have a catch all _, GHC complains about overlapping patterns. Easily solved with show <$> hmi_language inf.

changed weight to 3

added GHC API Tfeature request Trac import labels

changed title from Show instance for Language in DynFlags to Pretty Printer for textual version of Language (name) in DynFlags

to further clarify, based upon further discussion on IRC,

[23:39:41] <Fuuzetsu>	 Yep, all I want is Language -> String out of 
only having DynFlags which provides Maybe Language.

Its worth noting that this probably shouldn't be a show instance, because Language Standards need not have only the form (capital letter)(aphanumeric*).

The key point is a function to pretty print the name of the Language should be exposed. And probably more future proof to funny names if its not done via Show specifically.

ie

renderLanguageName :: Language -> String 

or the like

OK with me; maybe send patch?

Simon

added newcomer label

assigned to @trac-seraphime

closed

changed the description

changed milestone to %8.0.1

Trac metadata

Trac field	Value
Resolution	Unresolved → ResolvedFixed

An Outputable instance for this was added in 2ad46a86.

added Plow label