From e25b703805a6d5b20ddcb70e406830ca8d16cd22 Mon Sep 17 00:00:00 2001
From: Jed Barber <jjbarber@y7mail.com>
Date: Fri, 21 Feb 2014 23:51:29 +1100
Subject: Revised programming style

---
 fractran.hs | 15 ++++-----------
 makefile    |  4 ++--
 thue.hs     | 15 ++++-----------
 3 files changed, 10 insertions(+), 24 deletions(-)

diff --git a/fractran.hs b/fractran.hs
index 7f3946f..964a095 100644
--- a/fractran.hs
+++ b/fractran.hs
@@ -1,16 +1,11 @@
 
 import System.Environment( getArgs )
 import Data.Typeable
-import qualified Control.Exception
+import Control.Exception( ErrorCall(..), Handler(..), catches )
 import Fractran.Parser
 import Fractran.Interpreter
 
 
-data FractranException = FractranException { errString :: String }
-    deriving (Show, Typeable)
-
-instance Control.Exception.Exception FractranException
-
 
 
 usageString :: String
@@ -22,7 +17,7 @@ program :: IO ()
 program = do
 	args <- getArgs
 	fileContents <- if (length args /= 1)
-		            then Control.Exception.throw (FractranException usageString)
+		            then error usageString
 		            else readFile (head args)
 
 	case (parseFractran fileContents) of
@@ -31,8 +26,6 @@ program = do
 
 
 
-main = Control.Exception.catch program handler
-        where
-        	handler :: FractranException -> IO ()
-        	handler err = putStrLn (errString err)
+main = catches program
+               [ Handler ((\e -> putStrLn . show $ e) :: ErrorCall -> IO ()) ]
 
diff --git a/makefile b/makefile
index 961af1a..b702844 100644
--- a/makefile
+++ b/makefile
@@ -21,8 +21,8 @@ testprog:
 	ghc --make test.hs -o ${OUTPUTDIR}/test
 
 fractranprog:
-	ghc -XDeriveDataTypeable --make fractran.hs -o ${OUTPUTDIR}/fractran
+	ghc --make fractran.hs -o ${OUTPUTDIR}/fractran
 
 thueprog:
-	ghc -XDeriveDataTypeable --make thue.hs -o ${OUTPUTDIR}/thue
+	ghc --make thue.hs -o ${OUTPUTDIR}/thue
 
diff --git a/thue.hs b/thue.hs
index 6630e6d..7bc375d 100644
--- a/thue.hs
+++ b/thue.hs
@@ -1,16 +1,11 @@
 
 import System.Environment( getArgs )
 import Data.Typeable
-import qualified Control.Exception
+import Control.Exception( ErrorCall(..), Handler(..), catches )
 import Thue.Parser
 import Thue.Interpreter
 
 
-data ThueException = ThueException { errString :: String }
-    deriving (Show, Typeable)
-
-instance Control.Exception.Exception ThueException
-
 
 
 usageString :: String
@@ -22,7 +17,7 @@ program :: IO ()
 program = do
 	args <- getArgs
 	fileContents <- if (length args /= 1)
-		            then Control.Exception.throw (ThueException usageString)
+		            then error usageString
 		            else readFile (head args)
 
 	case (parseThue fileContents) of
@@ -31,8 +26,6 @@ program = do
 
 
 
-main = Control.Exception.catch program handler
-        where
-        	handler :: ThueException -> IO ()
-        	handler err = putStrLn (errString err)
+main = catches program
+               [ Handler ((\e -> putStrLn . show $ e) :: ErrorCall -> IO ()) ]
 
-- 
cgit