Changing GHCMod as a library.

Language/Haskell/GhcMod/Debug.hs

@@ -0,0 +1,42 @@
+module Language.Haskell.GhcMod.Debug (debugInfo, debug) where
+
+import Control.Applicative
+import Control.Exception.IOChoice
+import Control.Monad
+import Data.List (intercalate)
+import Data.Maybe
+import GHC
+import Language.Haskell.GhcMod.CabalApi
+import Language.Haskell.GhcMod.GHCApi
+import Language.Haskell.GhcMod.Types
+import Prelude
+
+----------------------------------------------------------------
+
+debugInfo :: Options -> Cradle -> String -> String -> IO String
+debugInfo opt cradle ver fileName = unlines <$> debug opt cradle ver fileName
+
+debug :: Options -> Cradle -> String -> String -> IO [String]
+debug opt cradle ver fileName = do
+    (gopts, incDir, pkgs) <-
+        if cabal then
+            fromCabalFile (ghcOpts opt) cradle ||> return (ghcOpts opt, [], [])
+          else
+            return (ghcOpts opt, [], [])
+    [fast] <- withGHC fileName $ do
+        void $ initializeFlagsWithCradle opt cradle gopts True
+        setTargetFile fileName
+        pure . canCheckFast <$> depanal [] False
+    return [
+        "GHC version:         " ++ ver
+      , "Current directory:   " ++ currentDir
+      , "Cabal file:          " ++ cabalFile
+      , "GHC options:         " ++ unwords gopts
+      , "Include directories: " ++ unwords incDir
+      , "Dependent packages:  " ++ intercalate ", " pkgs
+      , "Fast check:          " ++ if fast then "Yes" else "No"
+      ]
+  where
+    currentDir = cradleCurrentDir cradle
+    cabal = isJust $ cradleCabalFile cradle
+    cabalFile = fromMaybe "" $ cradleCabalFile cradle