+#!/usr/bin/env runhaskell
+\begin{code}
+{-# OPTIONS -Wall #-}
+
+import Control.Monad
+import Data.List
+import Distribution.PackageDescription
+import Distribution.Simple
+import Distribution.Simple.LocalBuildInfo
+import Distribution.Simple.Utils
+import System.Cmd
+import System.FilePath
+import System.Exit
+import System.Directory
+import Control.Exception (try)
+
+main :: IO ()
+main = do
+ let hooks = defaultUserHooks {
+ buildHook = build_primitive_sources
+ $ buildHook defaultUserHooks
+ }
+ defaultMainWithHooks hooks
+\end{code}
+
+Mostly snarfed from ghc-prim's Setup.hs.
+
+\begin{code}
+type Hook a = PackageDescription -> LocalBuildInfo -> UserHooks -> a -> IO ()
+
+build_primitive_sources :: Hook a -> Hook a
+build_primitive_sources f pd lbi uhs x
+ = do when (compilerFlavor (compiler lbi) == GHC) $ do
+ let genprimopcode = joinPath ["..", "..", "utils",
+ "genprimopcode", "genprimopcode"]
+ primops = joinPath ["..", "..", "compiler", "prelude",
+ "primops.txt"]
+ primhs = joinPath ["Language", "Core", "PrimEnv.hs"]
+ primhs_tmp = addExtension primhs "tmp"
+ maybeExit $ system (genprimopcode ++ " --make-ext-core-source < "
+ ++ primops ++ " > " ++ primhs_tmp)
+ maybeUpdateFile primhs_tmp primhs
+ maybeExit $ system ("make -C lib/GHC_ExtCore")
+ f pd lbi uhs x
+
+-- Replace a file only if the new version is different from the old.
+-- This prevents make from doing unnecessary work after we run 'setup makefile'
+maybeUpdateFile :: FilePath -> FilePath -> IO ()
+maybeUpdateFile source target = do
+ r <- rawSystem "cmp" ["-s" {-quiet-}, source, target]
+ case r of
+ ExitSuccess -> removeFile source
+ ExitFailure _ -> do try (removeFile target); renameFile source target
+
+
+\end{code}
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