Re: Haskell Extensions in various compilers (Cabal)

26 Jul 2004

      Isaac Jones  writes:

(snip)
...
Malcolm Wallace  writes:
...
Or, if you mean something like
    data Dummy a;
then how about EmptyDataDecls or VoidDataTypes?
Yep, that's what I meant.  I'll call them VoidDataTypes.  Thanks!
Oops. I just changed my mind.  I'll call them EmptyDataDecls, since I
think that's easier to undrestand, even though it's harder to say.

FWIW, Malcolm mentioned that it's implemented in nhc98 and can't be
turned off.  The same seems to be true of Hugs.  GHC, OTOH requires
-fglasgow-exts.

Just for fun, I'll provide the list again here, since this seems to be
the complete list of extensions, and how they are implemented by GHC,
NHC, and Hugs.

peace,

  isaac

data Extension = 
	       OverlappingInstances
               | RecursiveDo
               | ParallelListComp
               | MultiParamTypeClasses
               | NoMonomorphismRestriction
               | FunctionalDependencies
               | RankNTypes
               | PolymorphicComponents
               | ExistentialQuantification
               | ScopedTypeVariables
               | ImplicitParams
               | FlexibleContexts
               | FlexibleInstances
               | EmptyDataDecls

	       | TypeSynonymInstances
	       | TemplateHaskell
               | ForeignFunctionInterface
               | AllowOverlappingInstances
               | AllowUndecidableInstances
               | AllowIncoherentInstances
               | InlinePhase
               | ContextStack
               | Arrows
               | Generics
               | NoImplicitPrelude
               | NamedFieldPuns

               | ExtensibleRecords
               | RestrictedTypeSynonyms
               | HereDocuments
               | UnsafeOverlappingInstances
	       deriving (Show, Read, Eq)

-- |GHC: Return the unsupported extensions, and the flags for the supported extensions
extensionsToGHCFlag :: [ Extension ] -> ([Extension], [Opt])
extensionsToGHCFlag l
    = splitEither $ nub $ map extensionToGHCFlag l
    where
    extensionToGHCFlag :: Extension -> Either Extension String
    extensionToGHCFlag OverlappingInstances         = Right "-fallow-overlapping-instances"
    extensionToGHCFlag TypeSynonymInstances         = Right "-fglasgow-exts"
    extensionToGHCFlag TemplateHaskell              = Right "-fth"
    extensionToGHCFlag ForeignFunctionInterface     = Right "-ffi"
    extensionToGHCFlag NoMonomorphismRestriction    = Right "-fno-monomorphism-restriction"
    extensionToGHCFlag AllowOverlappingInstances    = Right "-fallow-overlapping-instances"
    extensionToGHCFlag AllowUndecidableInstances    = Right "-fallow-undecidable-instances"
    extensionToGHCFlag AllowIncoherentInstances     = Right "-fallow-incoherent-instances"
    extensionToGHCFlag InlinePhase                  = Right "-finline-phase"
    extensionToGHCFlag ContextStack                 = Right "-fcontext-stack"
    extensionToGHCFlag Arrows                       = Right "-farrows"
    extensionToGHCFlag Generics                     = Right "-fgenerics"
    extensionToGHCFlag NoImplicitPrelude            = Right "-fno-implicit-prelude"
    extensionToGHCFlag ImplicitParams               = Right "-fimplicit-params"

    extensionToGHCFlag RecursiveDo                  = Right "-fglasgow-exts"
    extensionToGHCFlag ParallelListComp             = Right "-fglasgow-exts"
    extensionToGHCFlag MultiParamTypeClasses        = Right "-fglasgow-exts"
    extensionToGHCFlag FunctionalDependencies       = Right "-fglasgow-exts"
    extensionToGHCFlag RankNTypes                   = Right "-fglasgow-exts"
    extensionToGHCFlag PolymorphicComponents        = Right "-fglasgow-exts"
    extensionToGHCFlag ExistentialQuantification    = Right "-fglasgow-exts"
    extensionToGHCFlag ScopedTypeVariables          = Right "-fglasgow-exts"
    extensionToGHCFlag FlexibleContexts             = Right "-fglasgow-exts"
    extensionToGHCFlag FlexibleInstances            = Right "-fglasgow-exts"
    extensionToGHCFlag EmptyDataDecls               = Right "-fglasgow-exts"

    extensionToGHCFlag e@ExtensibleRecords          = Left e
    extensionToGHCFlag e@RestrictedTypeSynonyms     = Left e
    extensionToGHCFlag e@HereDocuments              = Left e
    extensionToGHCFlag e@UnsafeOverlappingInstances = Left e
    extensionToGHCFlag e@NamedFieldPuns             = Left e

-- |NHC: Return the unsupported extensions, and the flags for the supported extensions
extensionsToNHCFlag :: [ Extension ] -> ([Extension], [Opt])
extensionsToNHCFlag l
    = splitEither $ nub $ map extensionToNHCFlag l
      where
      extensionToNHCFlag NoMonomorphismRestriction = Right "" -- not implemented in NHC
      extensionToNHCFlag ForeignFunctionInterface  = Right ""
      extensionToNHCFlag ExistentialQuantification = Right ""
      extensionToNHCFlag EmptyDataDecls            = Right ""
      extensionToNHCFlag NamedFieldPuns            = Right "-puns"
      extensionToNHCFlag e                         = Left e

-- |Hugs: Return the unsupported extensions, and the flags for the supported extensions
extensionsToHugsFlag :: [ Extension ] -> ([Extension], [Opt])
extensionsToHugsFlag l
    = splitEither $ nub $ map extensionToHugsFlag l
      where
      extensionToHugsFlag OverlappingInstances       = Right "+o"
      extensionToHugsFlag UnsafeOverlappingInstances = Right "+O"
      extensionToHugsFlag HereDocuments              = Right "+H"
      extensionToHugsFlag RecursiveDo                = Right "-98"
      extensionToHugsFlag ParallelListComp           = Right "-98"
      extensionToHugsFlag MultiParamTypeClasses      = Right "-98"
      extensionToHugsFlag FunctionalDependencies     = Right "-98"
      extensionToHugsFlag RankNTypes                 = Right "-98"
      extensionToHugsFlag PolymorphicComponents      = Right "-98"
      extensionToHugsFlag ExistentialQuantification  = Right "-98"
      extensionToHugsFlag ScopedTypeVariables        = Right "-98"
      extensionToHugsFlag ImplicitParams             = Right "-98"
      extensionToHugsFlag ExtensibleRecords          = Right "-98"
      extensionToHugsFlag RestrictedTypeSynonyms     = Right "-98"
      extensionToHugsFlag FlexibleContexts           = Right "-98"
      extensionToHugsFlag FlexibleInstances          = Right "-98"
      extensionToHugsFlag EmptyDataDecls             = Right ""
      extensionToHugsFlag e                          = Left e