adding some utils

ghci-lib/Language/Haskell/GHC/Util.hs

+module Language.Haskell.GHC.Util where
+
+import GhcMonad
+import GHC
+import DynFlags
+import Outputable
+import Packages
+import Module
+import qualified Pretty
+import FastString
+
+doc :: GhcMonad m => SDoc -> m String
+doc sdoc = do
+  flags <- getSessionDynFlags
+  unqual <- getPrintUnqual
+  let style = mkUserStyle unqual AllTheWay
+  let cols = pprCols flags
+      d = runSDoc sdoc (initSDocContext flags style)
+  return $ Pretty.fullRender Pretty.PageMode cols 1.5 string_txt "" d
+  where
+    string_txt :: Pretty.TextDetails -> String -> String
+    string_txt (Pretty.Chr c)   s  = c:s
+    string_txt (Pretty.Str s1)  s2 = s1 ++ s2
+    string_txt (Pretty.PStr s1) s2 = unpackFS s1 ++ s2
+    string_txt (Pretty.LStr s1 _) s2 = unpackLitString s1 ++ s2