Reduce IS_WINDOWS CPP

lib/GHCup/Utils/Prelude/Posix.hs

@@ -0,0 +1,20 @@
+module GHCup.Utils.Prelude.Posix where
+
+import System.Directory
+import System.Posix.Files
+
+
+isWindows, isNotWindows :: Bool
+isWindows = False
+isNotWindows = not isWindows
+
+
+moveFile :: FilePath -> FilePath -> IO ()
+moveFile = rename
+
+
+moveFilePortable :: FilePath -> FilePath -> IO ()
+moveFilePortable from to = do
+  copyFile from to
+  removeFile from
+  

lib/GHCup/Utils/Prelude/Windows.hs

@@ -0,0 +1,17 @@
+module GHCup.Utils.Prelude.Windows where
+
+import qualified System.Win32.File             as Win32
+
+
+isWindows, isNotWindows :: Bool
+isWindows = True
+isNotWindows = not isWindows
+
+
+moveFile :: FilePath -> FilePath -> IO ()
+moveFile from to = Win32.moveFileEx from (Just to) 0
+
+
+moveFilePortable :: FilePath -> FilePath -> IO ()
+moveFilePortable = Win32.moveFile
+