#8207: Pretty Printer for textual version of Language (name) in DynFlags -------------------------------------+------------------------------------- Reporter: Fuuzetsu | Owner: seraphime Type: feature request | Status: closed Priority: low | Milestone: 8.0.1 Component: GHC API | Version: 7.7 Resolution: fixed | Keywords: newcomer Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by bgamari): * status: new => closed * resolution: => fixed * milestone: => 8.0.1 @@ -7,1 +7,1 @@ - {{{ + {{{#!hs New description: 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 {{{#!hs 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`. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8207#comment:5 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler