From 1b4fdf35dd6c21d600130c42a1bcb5c56b25afa6 Mon Sep 17 00:00:00 2001
From: Sam T <pxqr.sta@gmail.com>
Date: Tue, 11 Jun 2013 06:00:57 +0400
Subject: ~ Use exception in fromFile.

Again, the problem is that one function returns errors in two different
ways: Either and IO exceptions. It's better to just throw exception in
either case.
---
 exsamples/Main.hs         | 2 +-
 src/Data/Torrent.hs       | 6 ++++--
 src/Network/BitTorrent.hs | 2 ++
 tests/InfoHash.hs         | 2 +-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/exsamples/Main.hs b/exsamples/Main.hs
index 3a347ab6..b0224886 100644
--- a/exsamples/Main.hs
+++ b/exsamples/Main.hs
@@ -8,7 +8,7 @@ import System.Environment
 main :: IO ()
 main = do
   [path] <- getArgs
-  Right torrent <- fromFile path
+  torrent <- fromFile path
 
   client  <- newClient []
   swarm   <- newLeacher  client torrent
diff --git a/src/Data/Torrent.hs b/src/Data/Torrent.hs
index 3175e151..068e9cb6 100644
--- a/src/Data/Torrent.hs
+++ b/src/Data/Torrent.hs
@@ -55,6 +55,8 @@ import Prelude hiding (sum)
 
 import Control.Applicative
 import Control.Arrow
+import Control.Exception
+import Control.Monad
 import Data.BEncode as BE
 import Data.Char
 import Data.Foldable
@@ -353,8 +355,8 @@ isMultiFile MultiFile {} = True
 isMultiFile _            = False
 
 -- | Read and decode a .torrent file.
-fromFile :: FilePath -> IO (Result Torrent)
-fromFile filepath = decoded <$> B.readFile filepath
+fromFile :: FilePath -> IO Torrent
+fromFile = B.readFile >=> either (throwIO . userError) return . decoded
 
 {-----------------------------------------------------------------------
     Info hash
diff --git a/src/Network/BitTorrent.hs b/src/Network/BitTorrent.hs
index 61185d08..c37129cb 100644
--- a/src/Network/BitTorrent.hs
+++ b/src/Network/BitTorrent.hs
@@ -28,6 +28,8 @@ import Network.BitTorrent.Peer as BT
 import Network.BitTorrent.Exchange as BT
 import Network.BitTorrent.Tracker as BT
 
+-- discover should hide tracker and DHT communication under the hood
+-- thus we can obtain unified interface
 
 discover :: SwarmSession -> (TSession -> IO a) -> IO a
 discover SwarmSession {..} action = do
diff --git a/tests/InfoHash.hs b/tests/InfoHash.hs
index dbbcbf53..3f5a1432 100644
--- a/tests/InfoHash.hs
+++ b/tests/InfoHash.hs
@@ -19,7 +19,7 @@ main = do
   args <- getArgs
   let path = if length args == 0 then torrentFileName else head args
 
-  Right t <- fromFile path
+  t <- fromFile path
 
   BC.putStr "info hash: "
   print (ppInfoHash (tInfoHash t))
-- 
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