Some refactorings

install/src/Cabal.hs

@@ -17,7 +17,6 @@ import           Version
 import           Print
 import           Env
 import           Stack
-import           Debug.Trace
 
 execCabal :: CmdResult r => [String] -> Action r
 execCabal = execCabalWithOriginalPath
@@ -76,19 +75,17 @@ cabalInstallHie versionNumber = do
              ++ minorVerExe
              ++ " to " ++ localBin
 
-installCabal :: Action ()
-installCabal = do
+installCabalWithStack :: Action ()
+installCabalWithStack = do
   -- try to find existing `cabal` executable with appropriate version
-  cabalExeOk <- do
-    c <- withOriginalPath (liftIO (findExecutable "cabal"))
-    liftIO $ traceIO $ show c
-    when (isJust c) checkCabal
-    return $ isJust c
-  
-  -- install `cabal-install` if not already installed
-  if cabalExeOk
-    then printLine "There is already a cabal executable in $PATH with the required minimum version."
-    else execStackShake_ ["install", "cabal-install"]
+  mbc <- withOriginalPath (liftIO (findExecutable "cabal"))
+
+  case mbc of
+    Just c  -> do
+      checkCabal
+      printLine "There is already a cabal executable in $PATH with the required minimum version."
+     -- install `cabal-install` if not already installed
+    Nothing ->  execStackShake_ ["install", "cabal-install"]
 
 -- | check `cabal` has the required version
 checkCabal :: Action ()
@@ -122,7 +119,7 @@ cabalInstallNotSuportedFailMsg =
 -- | Error message when the `cabal` binary is an older version
 cabalInstallIsOldFailMsg :: String -> String
 cabalInstallIsOldFailMsg cabalVersion =
-  "The `cabal` executable is outdated.\n"
+  "The `cabal` executable found in $PATH is outdated.\n"
     ++ "found version is `"
     ++ cabalVersion
     ++ "`.\n"

install/src/HieInstall.hs

@@ -63,7 +63,7 @@ defaultMain = do
     want ["short-help"]
     -- general purpose targets
     phony "submodules"  updateSubmodules
-    phony "cabal"       installCabal
+    phony "cabal"       installCabalWithStack
     phony "short-help"  shortHelpMessage
     phony "all"         shortHelpMessage
     phony "help"        (helpMessage versions)

install/src/Stack.hs

@@ -104,7 +104,7 @@ withOriginalPath :: Action a -> Action a
 withOriginalPath action = do
   mbPath <- liftIO (lookupEnv "PATH")
 
-  case (mbPath,isRunFromStack) of
+  case (mbPath, isRunFromStack) of
 
     (Just paths, True) -> do
       snapshotDir <- trimmedStdout <$> execStackShake ["path", "--snapshot-install-root"]
@@ -122,7 +122,8 @@ withOriginalPath action = do
     otherwise -> action
 
   where removePathsContaining str path =
-          intercalate [searchPathSeparator] (filter (not.(isInfixOf str)) (splitPaths path))
+           joinPaths (filter (not.(isInfixOf str)) (splitPaths path))
+        joinPaths = intercalate [searchPathSeparator]
         splitPaths s =
           case dropWhile (== searchPathSeparator) s of
                       "" -> []