+expandEnvVars :: PackageConfig -> Bool -> IO PackageConfig
+expandEnvVars pkg force = do
+ -- permit _all_ strings to contain ${..} environment variable references,
+ -- arguably too flexible.
+ nm <- expandString (name pkg)
+ imp_dirs <- expandStrings (import_dirs pkg)
+ src_dirs <- expandStrings (source_dirs pkg)
+ lib_dirs <- expandStrings (library_dirs pkg)
+ hs_libs <- expandStrings (hs_libraries pkg)
+ ex_libs <- expandStrings (extra_libraries pkg)
+ inc_dirs <- expandStrings (include_dirs pkg)
+ c_incs <- expandStrings (c_includes pkg)
+ p_deps <- expandStrings (package_deps pkg)
+ e_g_opts <- expandStrings (extra_ghc_opts pkg)
+ e_c_opts <- expandStrings (extra_cc_opts pkg)
+ e_l_opts <- expandStrings (extra_ld_opts pkg)
+ f_dirs <- expandStrings (framework_dirs pkg)
+ e_frames <- expandStrings (extra_frameworks pkg)
+ return (pkg { name = nm
+ , import_dirs = imp_dirs
+ , source_dirs = src_dirs
+ , library_dirs = lib_dirs
+ , hs_libraries = hs_libs
+ , extra_libraries = ex_libs
+ , include_dirs = inc_dirs
+ , c_includes = c_incs
+ , package_deps = p_deps
+ , extra_ghc_opts = e_g_opts
+ , extra_cc_opts = e_c_opts
+ , extra_ld_opts = e_l_opts
+ , framework_dirs = f_dirs
+ , extra_frameworks= e_frames
+ })
+ where
+ expandStrings = mapM expandString
+
+ -- Just for fun, keep this in the IO monad.
+ expandString :: String -> IO String
+ expandString str =
+ case break (=='$') str of
+ (xs, _:'{':rs) ->
+ case span (/='}') rs of
+ (nm,_:remainder) -> do
+ nm' <- lookupEnvVar nm
+ str' <- expandString remainder
+ return (nm' ++ str')
+ _ -> return str -- no closing '}'
+ _ -> return str
+
+ lookupEnvVar nm =
+ catch (System.getEnv nm)
+ (\ _ -> do dieOrForce force ("Unable to expand variable " ++
+ show nm)
+ return "")
+
+-----------------------------------------------------------------------------