    {-# LANGUAGE FlexibleContexts #-}
    {-# LANGUAGE RankNTypes #-}
    -----------------------------------------------------------------------------
    -- |
    -- Module      :  Distribution.Simple.BuildPaths
    -- Copyright   :  Isaac Jones 2003-2004,
    --                Duncan Coutts 2008
    -- License     :  BSD3
    --
    -- Maintainer  :  cabal-devel@haskell.org
    -- Portability :  portable
    --
    -- A bunch of dirs, paths and file names used for intermediate build steps.
    --

    module Distribution.Simple.BuildPaths (
        defaultDistPref, srcPref,
        haddockDirName, hscolourPref, haddockPref,
        autogenPackageModulesDir,
        autogenComponentModulesDir,

        autogenPathsModuleName,
        cppHeaderName,
        haddockName,

        mkGenericStaticLibName,
        mkLibName,
        mkProfLibName,
        mkGenericSharedLibName,
        mkSharedLibName,
        mkStaticLibName,
        mkGenericSharedBundledLibName,

        exeExtension,
        objExtension,
        dllExtension,
        staticLibExtension,
        -- * Source files & build directories
        getSourceFiles, getLibSourceFiles, getExeSourceFiles,
        getFLibSourceFiles, exeBuildDir, flibBuildDir,
      ) where

    import Prelude ()
    import Distribution.Compat.Prelude

    import Distribution.Package
    import Distribution.ModuleName as ModuleName
    import Distribution.Compiler
    import Distribution.PackageDescription
    import Distribution.Simple.LocalBuildInfo
    import Distribution.Simple.Setup
    import Distribution.Pretty
    import Distribution.System
    import Distribution.Verbosity
    import Distribution.Simple.Utils
    import Distribution.Utils.Path

    import Data.List (stripPrefix)
    import System.FilePath ((</>), (<.>), normalise)

    -- ---------------------------------------------------------------------------
    -- Build directories and files

    srcPref :: FilePath -> FilePath
    srcPref :: String -> String
    srcPref String
    distPref = String
    distPref String -> String -> String
    </> String
    "src"

    hscolourPref :: HaddockTarget -> FilePath -> PackageDescription -> FilePath
    hscolourPref :: HaddockTarget -> String -> PackageDescription -> String
    hscolourPref = HaddockTarget -> String -> PackageDescription -> String
    haddockPref

    -- | This is the name of the directory in which the generated haddocks
    -- should be stored. It does not include the @<dist>/doc/html@ prefix.
    haddockDirName :: HaddockTarget -> PackageDescription -> FilePath
    haddockDirName :: HaddockTarget -> PackageDescription -> String
    haddockDirName HaddockTarget
    ForDevelopment = PackageName -> String
    forall a. Pretty a => a -> String
    prettyShow (PackageName -> String)
    -> (PackageDescription -> PackageName)
    -> PackageDescription
    -> String
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . PackageDescription -> PackageName
    forall pkg. Package pkg => pkg -> PackageName
    packageName
    haddockDirName HaddockTarget
    ForHackage = (String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    "-docs") (String -> String)
    -> (PackageDescription -> String) -> PackageDescription -> String
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . PackageIdentifier -> String
    forall a. Pretty a => a -> String
    prettyShow (PackageIdentifier -> String)
    -> (PackageDescription -> PackageIdentifier)
    -> PackageDescription
    -> String
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . PackageDescription -> PackageIdentifier
    forall pkg. Package pkg => pkg -> PackageIdentifier
    packageId

    -- | The directory to which generated haddock documentation should be written.
    haddockPref :: HaddockTarget -> FilePath -> PackageDescription -> FilePath
    haddockPref :: HaddockTarget -> String -> PackageDescription -> String
    haddockPref HaddockTarget
    haddockTarget String
    distPref PackageDescription
    pkg_descr
        = String
    distPref String -> String -> String
    </> String
    "doc" String -> String -> String
    </> String
    "html" String -> String -> String
    </> HaddockTarget -> PackageDescription -> String
    haddockDirName HaddockTarget
    haddockTarget PackageDescription
    pkg_descr

    -- | The directory in which we put auto-generated modules for EVERY
    -- component in the package.
    autogenPackageModulesDir :: LocalBuildInfo -> String
    autogenPackageModulesDir :: LocalBuildInfo -> String
    autogenPackageModulesDir LocalBuildInfo
    lbi = LocalBuildInfo -> String
    buildDir LocalBuildInfo
    lbi String -> String -> String
    </> String
    "global-autogen"

    -- | The directory in which we put auto-generated modules for a
    -- particular component.
    autogenComponentModulesDir :: LocalBuildInfo -> ComponentLocalBuildInfo -> String
    autogenComponentModulesDir :: LocalBuildInfo -> ComponentLocalBuildInfo -> String
    autogenComponentModulesDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi = LocalBuildInfo -> ComponentLocalBuildInfo -> String
    componentBuildDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi String -> String -> String
    </> String
    "autogen"
    -- NB: Look at 'checkForeignDeps' for where a simplified version of this
    -- has been copy-pasted.

    cppHeaderName :: String
    cppHeaderName :: String
    cppHeaderName = String
    "cabal_macros.h"

    -- | The name of the auto-generated Paths_* module associated with a package
    autogenPathsModuleName :: PackageDescription -> ModuleName
    autogenPathsModuleName :: PackageDescription -> ModuleName
    autogenPathsModuleName PackageDescription
    pkg_descr =
      String -> ModuleName
    forall a. IsString a => String -> a
    ModuleName.fromString (String -> ModuleName) -> String -> ModuleName
    forall a b. (a -> b) -> a -> b
    $
        String
    "Paths_" String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ (Char -> Char) -> String -> String
    forall a b. (a -> b) -> [a] -> [b]
    map Char -> Char
    fixchar (PackageName -> String
    forall a. Pretty a => a -> String
    prettyShow (PackageDescription -> PackageName
    forall pkg. Package pkg => pkg -> PackageName
    packageName PackageDescription
    pkg_descr))
      where fixchar :: Char -> Char
    fixchar Char
    '-' = Char
    '_'
            fixchar Char
    c   = Char
    c

    haddockName :: PackageDescription -> FilePath
    haddockName :: PackageDescription -> String
    haddockName PackageDescription
    pkg_descr = PackageName -> String
    forall a. Pretty a => a -> String
    prettyShow (PackageDescription -> PackageName
    forall pkg. Package pkg => pkg -> PackageName
    packageName PackageDescription
    pkg_descr) String -> String -> String
    <.> String
    "haddock"

    -- -----------------------------------------------------------------------------
    -- Source File helper

    getLibSourceFiles :: Verbosity
                         -> LocalBuildInfo
                         -> Library
                         -> ComponentLocalBuildInfo
                         -> IO [(ModuleName.ModuleName, FilePath)]
    getLibSourceFiles :: Verbosity
    -> LocalBuildInfo
    -> Library
    -> ComponentLocalBuildInfo
    -> IO [(ModuleName, String)]
    getLibSourceFiles Verbosity
    verbosity LocalBuildInfo
    lbi Library
    lib ComponentLocalBuildInfo
    clbi = Verbosity -> [String] -> [ModuleName] -> IO [(ModuleName, String)]
    getSourceFiles Verbosity
    verbosity [String]
    searchpaths [ModuleName]
    modules
      where
        bi :: BuildInfo
    bi               = Library -> BuildInfo
    libBuildInfo Library
    lib
        modules :: [ModuleName]
    modules          = Library -> ComponentLocalBuildInfo -> [ModuleName]
    allLibModules Library
    lib ComponentLocalBuildInfo
    clbi
        searchpaths :: [String]
    searchpaths      = LocalBuildInfo -> ComponentLocalBuildInfo -> String
    componentBuildDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : (SymbolicPath PackageDir SourceDir -> String)
    -> [SymbolicPath PackageDir SourceDir] -> [String]
    forall a b. (a -> b) -> [a] -> [b]
    map SymbolicPath PackageDir SourceDir -> String
    forall from to. SymbolicPath from to -> String
    getSymbolicPath (BuildInfo -> [SymbolicPath PackageDir SourceDir]
    hsSourceDirs BuildInfo
    bi) [String] -> [String] -> [String]
    forall a. [a] -> [a] -> [a]
    ++
                         [ LocalBuildInfo -> ComponentLocalBuildInfo -> String
    autogenComponentModulesDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi
                         , LocalBuildInfo -> String
    autogenPackageModulesDir LocalBuildInfo
    lbi ]

    getExeSourceFiles :: Verbosity
                         -> LocalBuildInfo
                         -> Executable
                         -> ComponentLocalBuildInfo
                         -> IO [(ModuleName.ModuleName, FilePath)]
    getExeSourceFiles :: Verbosity
    -> LocalBuildInfo
    -> Executable
    -> ComponentLocalBuildInfo
    -> IO [(ModuleName, String)]
    getExeSourceFiles Verbosity
    verbosity LocalBuildInfo
    lbi Executable
    exe ComponentLocalBuildInfo
    clbi = do
        [(ModuleName, String)]
    moduleFiles <- Verbosity -> [String] -> [ModuleName] -> IO [(ModuleName, String)]
    getSourceFiles Verbosity
    verbosity [String]
    searchpaths [ModuleName]
    modules
        String
    srcMainPath <- Verbosity -> [String] -> String -> IO String
    findFileEx Verbosity
    verbosity ((SymbolicPath PackageDir SourceDir -> String)
    -> [SymbolicPath PackageDir SourceDir] -> [String]
    forall a b. (a -> b) -> [a] -> [b]
    map SymbolicPath PackageDir SourceDir -> String
    forall from to. SymbolicPath from to -> String
    getSymbolicPath ([SymbolicPath PackageDir SourceDir] -> [String])
    -> [SymbolicPath PackageDir SourceDir] -> [String]
    forall a b. (a -> b) -> a -> b
    $ BuildInfo -> [SymbolicPath PackageDir SourceDir]
    hsSourceDirs BuildInfo
    bi) (Executable -> String
    modulePath Executable
    exe)
        [(ModuleName, String)] -> IO [(ModuleName, String)]
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((ModuleName
    ModuleName.main, String
    srcMainPath) (ModuleName, String)
    -> [(ModuleName, String)] -> [(ModuleName, String)]
    forall a. a -> [a] -> [a]
    : [(ModuleName, String)]
    moduleFiles)
      where
        bi :: BuildInfo
    bi          = Executable -> BuildInfo
    buildInfo Executable
    exe
        modules :: [ModuleName]
    modules     = BuildInfo -> [ModuleName]
    otherModules BuildInfo
    bi
        searchpaths :: [String]
    searchpaths = LocalBuildInfo -> ComponentLocalBuildInfo -> String
    autogenComponentModulesDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi
                    String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : LocalBuildInfo -> String
    autogenPackageModulesDir LocalBuildInfo
    lbi
                    String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : LocalBuildInfo -> Executable -> String
    exeBuildDir LocalBuildInfo
    lbi Executable
    exe String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : (SymbolicPath PackageDir SourceDir -> String)
    -> [SymbolicPath PackageDir SourceDir] -> [String]
    forall a b. (a -> b) -> [a] -> [b]
    map SymbolicPath PackageDir SourceDir -> String
    forall from to. SymbolicPath from to -> String
    getSymbolicPath (BuildInfo -> [SymbolicPath PackageDir SourceDir]
    hsSourceDirs BuildInfo
    bi)

    getFLibSourceFiles :: Verbosity
                       -> LocalBuildInfo
                       -> ForeignLib
                       -> ComponentLocalBuildInfo
                       -> IO [(ModuleName.ModuleName, FilePath)]
    getFLibSourceFiles :: Verbosity
    -> LocalBuildInfo
    -> ForeignLib
    -> ComponentLocalBuildInfo
    -> IO [(ModuleName, String)]
    getFLibSourceFiles Verbosity
    verbosity LocalBuildInfo
    lbi ForeignLib
    flib ComponentLocalBuildInfo
    clbi = Verbosity -> [String] -> [ModuleName] -> IO [(ModuleName, String)]
    getSourceFiles Verbosity
    verbosity [String]
    searchpaths [ModuleName]
    modules
      where
        bi :: BuildInfo
    bi          = ForeignLib -> BuildInfo
    foreignLibBuildInfo ForeignLib
    flib
        modules :: [ModuleName]
    modules     = BuildInfo -> [ModuleName]
    otherModules BuildInfo
    bi
        searchpaths :: [String]
    searchpaths = LocalBuildInfo -> ComponentLocalBuildInfo -> String
    autogenComponentModulesDir LocalBuildInfo
    lbi ComponentLocalBuildInfo
    clbi
                    String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : LocalBuildInfo -> String
    autogenPackageModulesDir LocalBuildInfo
    lbi
                    String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : LocalBuildInfo -> ForeignLib -> String
    flibBuildDir LocalBuildInfo
    lbi ForeignLib
    flib String -> [String] -> [String]
    forall a. a -> [a] -> [a]
    : (SymbolicPath PackageDir SourceDir -> String)
    -> [SymbolicPath PackageDir SourceDir] -> [String]
    forall a b. (a -> b) -> [a] -> [b]
    map SymbolicPath PackageDir SourceDir -> String
    forall from to. SymbolicPath from to -> String
    getSymbolicPath (BuildInfo -> [SymbolicPath PackageDir SourceDir]
    hsSourceDirs BuildInfo
    bi)

    getSourceFiles :: Verbosity -> [FilePath]
                      -> [ModuleName.ModuleName]
                      -> IO [(ModuleName.ModuleName, FilePath)]
    getSourceFiles :: Verbosity -> [String] -> [ModuleName] -> IO [(ModuleName, String)]
    getSourceFiles Verbosity
    verbosity [String]
    dirs [ModuleName]
    modules = ((ModuleName -> IO (ModuleName, String))
     -> [ModuleName] -> IO [(ModuleName, String)])
    -> [ModuleName]
    -> (ModuleName -> IO (ModuleName, String))
    -> IO [(ModuleName, String)]
    forall a b c. (a -> b -> c) -> b -> a -> c
    flip (ModuleName -> IO (ModuleName, String))
    -> [ModuleName] -> IO [(ModuleName, String)]
    forall (t :: * -> *) (f :: * -> *) a b.
    (Traversable t, Applicative f) =>
    (a -> f b) -> t a -> f (t b)
    traverse [ModuleName]
    modules ((ModuleName -> IO (ModuleName, String))
     -> IO [(ModuleName, String)])
    -> (ModuleName -> IO (ModuleName, String))
    -> IO [(ModuleName, String)]
    forall a b. (a -> b) -> a -> b
    $ \ModuleName
    m -> (String -> (ModuleName, String))
    -> IO String -> IO (ModuleName, String)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap ((,) ModuleName
    m) (IO String -> IO (ModuleName, String))
    -> IO String -> IO (ModuleName, String)
    forall a b. (a -> b) -> a -> b
    $
        [String] -> [String] -> String -> IO (Maybe String)
    findFileWithExtension [String
    "hs", String
    "lhs", String
    "hsig", String
    "lhsig"] [String]
    dirs (ModuleName -> String
    ModuleName.toFilePath ModuleName
    m)
          IO (Maybe String) -> (Maybe String -> IO String) -> IO String
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= IO String -> (String -> IO String) -> Maybe String -> IO String
    forall b a. b -> (a -> b) -> Maybe a -> b
    maybe (ModuleName -> IO String
    forall {a} {a}. Pretty a => a -> IO a
    notFound ModuleName
    m) (String -> IO String
    forall (m :: * -> *) a. Monad m => a -> m a
    return (String -> IO String) -> (String -> String) -> String -> IO String
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . String -> String
    normalise)
      where
        notFound :: a -> IO a
    notFound a
    module_ = Verbosity -> String -> IO a
    forall a. Verbosity -> String -> IO a
    die' Verbosity
    verbosity (String -> IO a) -> String -> IO a
    forall a b. (a -> b) -> a -> b
    $ String
    "can't find source for module " String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ a -> String
    forall a. Pretty a => a -> String
    prettyShow a
    module_

    -- | The directory where we put build results for an executable
    exeBuildDir :: LocalBuildInfo -> Executable -> FilePath
    exeBuildDir :: LocalBuildInfo -> Executable -> String
    exeBuildDir LocalBuildInfo
    lbi Executable
    exe = LocalBuildInfo -> String
    buildDir LocalBuildInfo
    lbi String -> String -> String
    </> String
    nm String -> String -> String
    </> String
    nm String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    "-tmp"
      where
        nm :: String
    nm = UnqualComponentName -> String
    unUnqualComponentName (UnqualComponentName -> String) -> UnqualComponentName -> String
    forall a b. (a -> b) -> a -> b
    $ Executable -> UnqualComponentName
    exeName Executable
    exe

    -- | The directory where we put build results for a foreign library
    flibBuildDir :: LocalBuildInfo -> ForeignLib -> FilePath
    flibBuildDir :: LocalBuildInfo -> ForeignLib -> String
    flibBuildDir LocalBuildInfo
    lbi ForeignLib
    flib = LocalBuildInfo -> String
    buildDir LocalBuildInfo
    lbi String -> String -> String
    </> String
    nm String -> String -> String
    </> String
    nm String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    "-tmp"
      where
        nm :: String
    nm = UnqualComponentName -> String
    unUnqualComponentName (UnqualComponentName -> String) -> UnqualComponentName -> String
    forall a b. (a -> b) -> a -> b
    $ ForeignLib -> UnqualComponentName
    foreignLibName ForeignLib
    flib

    -- ---------------------------------------------------------------------------
    -- Library file names

    -- | Create a library name for a static library from a given name.
    -- Prepends @lib@ and appends the static library extension (@.a@).
    mkGenericStaticLibName :: String -> String
    mkGenericStaticLibName :: String -> String
    mkGenericStaticLibName String
    lib = String
    "lib" String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    lib String -> String -> String
    <.> String
    "a"

    mkLibName :: UnitId -> String
    mkLibName :: UnitId -> String
    mkLibName UnitId
    lib = String -> String
    mkGenericStaticLibName (UnitId -> String
    getHSLibraryName UnitId
    lib)

    mkProfLibName :: UnitId -> String
    mkProfLibName :: UnitId -> String
    mkProfLibName UnitId
    lib =  String -> String
    mkGenericStaticLibName (UnitId -> String
    getHSLibraryName UnitId
    lib String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    "_p")

    -- | Create a library name for a shared library from a given name.
    -- Prepends @lib@ and appends the @-\<compilerFlavour\>\<compilerVersion\>@
    -- as well as the shared library extension.
    mkGenericSharedLibName :: Platform -> CompilerId -> String -> String
    mkGenericSharedLibName :: Platform -> CompilerId -> String -> String
    mkGenericSharedLibName Platform
    platform (CompilerId CompilerFlavor
    compilerFlavor Version
    compilerVersion) String
    lib
      = [String] -> String
    forall a. Monoid a => [a] -> a
    mconcat [ String
    "lib", String
    lib, String
    "-", String
    comp String -> String -> String
    <.> Platform -> String
    dllExtension Platform
    platform ]
      where comp :: String
    comp = CompilerFlavor -> String
    forall a. Pretty a => a -> String
    prettyShow CompilerFlavor
    compilerFlavor String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ Version -> String
    forall a. Pretty a => a -> String
    prettyShow Version
    compilerVersion

    -- Implement proper name mangling for dynamical shared objects
    -- @libHS\<packagename\>-\<compilerFlavour\>\<compilerVersion\>@
    -- e.g. @libHSbase-2.1-ghc6.6.1.so@
    mkSharedLibName :: Platform -> CompilerId -> UnitId -> String
    mkSharedLibName :: Platform -> CompilerId -> UnitId -> String
    mkSharedLibName Platform
    platform CompilerId
    comp UnitId
    lib
      = Platform -> CompilerId -> String -> String
    mkGenericSharedLibName Platform
    platform CompilerId
    comp (UnitId -> String
    getHSLibraryName UnitId
    lib)

    -- Static libs are named the same as shared libraries, only with
    -- a different extension.
    mkStaticLibName :: Platform -> CompilerId -> UnitId -> String
    mkStaticLibName :: Platform -> CompilerId -> UnitId -> String
    mkStaticLibName Platform
    platform (CompilerId CompilerFlavor
    compilerFlavor Version
    compilerVersion) UnitId
    lib
      = String
    "lib" String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ UnitId -> String
    getHSLibraryName UnitId
    lib String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    "-" String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    comp String -> String -> String
    <.> Platform -> String
    staticLibExtension Platform
    platform
      where comp :: String
    comp = CompilerFlavor -> String
    forall a. Pretty a => a -> String
    prettyShow CompilerFlavor
    compilerFlavor String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ Version -> String
    forall a. Pretty a => a -> String
    prettyShow Version
    compilerVersion

    -- | Create a library name for a bundled shared library from a given name.
    -- This matches the naming convention for shared libraries as implemented in
    -- GHC's packageHsLibs function in the Packages module.
    -- If the given name is prefixed with HS, then this prepends 'lib' and appends
    -- the compiler flavour/version and shared library extension e.g.:
    --     "HSrts-1.0" -> "libHSrts-1.0-ghc8.7.20190109.so"
    -- Otherwise the given name should be prefixed with 'C', then this strips the
    -- 'C', prepends 'lib' and appends the shared library extension e.g.:
    --     "Cffi" -> "libffi.so"
    mkGenericSharedBundledLibName :: Platform -> CompilerId -> String -> String
    mkGenericSharedBundledLibName :: Platform -> CompilerId -> String -> String
    mkGenericSharedBundledLibName Platform
    platform CompilerId
    comp String
    lib
      | String
    "HS" String -> String -> Bool
    forall a. Eq a => [a] -> [a] -> Bool
    `isPrefixOf` String
    lib
        = Platform -> CompilerId -> String -> String
    mkGenericSharedLibName Platform
    platform CompilerId
    comp String
    lib
      | Just String
    lib' <- String -> String -> Maybe String
    forall a. Eq a => [a] -> [a] -> Maybe [a]
    stripPrefix String
    "C" String
    lib
        = String
    "lib" String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    lib' String -> String -> String
    <.> Platform -> String
    dllExtension Platform
    platform
      | Bool
    otherwise
        = String -> String
    forall a. HasCallStack => String -> a
    error (String
    "Don't understand library name " String -> String -> String
    forall a. [a] -> [a] -> [a]
    ++ String
    lib)

    -- ------------------------------------------------------------
    -- * Platform file extensions
    -- ------------------------------------------------------------

    -- | Default extension for executable files on the current platform.
    -- (typically @\"\"@ on Unix and @\"exe\"@ on Windows or OS\/2)
    exeExtension :: Platform -> String
    exeExtension :: Platform -> String
    exeExtension (Platform Arch
    _arch OS
    os) = case OS
    os of
                       OS
    Windows -> String
    "exe"
                       OS
    _       -> String
    ""

    -- | Extension for object files. For GHC the extension is @\"o\"@.
    objExtension :: String
    objExtension :: String
    objExtension = String
    "o"

    -- | Extension for dynamically linked (or shared) libraries
    -- (typically @\"so\"@ on Unix and @\"dll\"@ on Windows)
    dllExtension :: Platform -> String
    dllExtension :: Platform -> String
    dllExtension (Platform Arch
    _arch OS
    os)= case OS
    os of
                       OS
    Windows -> String
    "dll"
                       OS
    OSX     -> String
    "dylib"
                       OS
    _       -> String
    "so"

    -- | Extension for static libraries
    --
    -- TODO: Here, as well as in dllExtension, it's really the target OS that we're
    -- interested in, not the build OS.
    staticLibExtension :: Platform -> String
    staticLibExtension :: Platform -> String
    staticLibExtension (Platform Arch
    _arch OS
    os) = case OS
    os of
                           OS
    Windows -> String
    "lib"
                           OS
    _       -> String
    "a"