PGF2.hsc: use throwIO instead of throw

From the documentation: the throwIO variant should be used in preference to
throw to raise an exception within the IO monad because it guarantees ordering
with respect to other IO operations, whereas throw does not.

Also removed some unused imports.

1 files changed, 7 insertions, 11 deletions

diff --git a/src/runtime/haskell-bind/PGF2.hsc b/src/runtime/haskell-bind/PGF2.hsc
index 42d49deb4..d76e86a5d 100644
--- a/src/runtime/haskell-bind/PGF2.hsc
+++ b/src/runtime/haskell-bind/PGF2.hsc
@@ -16,18 +16,14 @@ module PGF2 (-- * PGF
             ) where
 
 import Prelude hiding (fromEnum)
-import Control.Exception
---import System.IO
-import System.IO.Unsafe
+import Control.Exception(Exception,throwIO)
+import System.IO.Unsafe(unsafePerformIO,unsafeInterleaveIO)
 import PGF2.FFI
 
 import Foreign hiding ( Pool, newPool, unsafePerformIO )
 import Foreign.C
---import Foreign.C.String
---import Foreign.Ptr
 import Data.Typeable
 import qualified Data.Map as Map
---import qualified Data.ByteString as BS
 import Data.IORef
 
  
@@ -58,7 +54,7 @@ readPGF fpath =
                                      gu_pool_free pool
                                      ioError (errnoToIOError "readPGF" (Errno errno) Nothing (Just fpath))
                              else do gu_pool_free pool
-                                     throw (PGFError "The grammar cannot be loaded")
+                                     throwIO (PGFError "The grammar cannot be loaded")
                    else return pgf
      master <- newForeignPtr gu_pool_finalizer pool
      return PGF {pgf = pgf, pgfMaster = master}
@@ -225,10 +221,10 @@ parse lang cat sent =
                                   msg <- peekCString c_msg
                                   gu_pool_free parsePl
                                   gu_pool_free exprPl
-                                  throw (PGFError msg)
+                                  throwIO (PGFError msg)
                           else do gu_pool_free parsePl
                                   gu_pool_free exprPl
-                                  throw (PGFError "Parsing failed")
+                                  throwIO (PGFError "Parsing failed")
          else do parseFPl <- newForeignPtr gu_pool_finalizer parsePl
                  exprFPl  <- newForeignPtr gu_pool_finalizer exprPl
                  exprs    <- fromPgfExprEnum enum parseFPl (lang,exprFPl)
@@ -248,8 +244,8 @@ linearize lang e = unsafePerformIO $
                    else if ty == gu_type__PgfExn
                           then do c_msg <- (#peek GuExn, data.data) exn
                                   msg <- peekCString c_msg
-                                  throw (PGFError msg)
-                          else throw (PGFError "The abstract tree cannot be linearized")
+                                  throwIO (PGFError msg)
+                          else throwIO (PGFError "The abstract tree cannot be linearized")
          else do lin <- gu_string_buf_freeze sb pl
                  peekCString lin