From 03fbbc3a9652372f64989c7cd3ab7583049f6a73 Mon Sep 17 00:00:00 2001
From: Tissevert <tissevert+devel@marvid.fr>
Date: Fri, 7 Feb 2020 13:08:10 +0100
Subject: [PATCH] Why did I implement this overly complicated lift by hand
 again ?

---
 src/PDF/Pages.hs | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/PDF/Pages.hs b/src/PDF/Pages.hs
index 31cdb6d..e7c61d6 100755
--- a/src/PDF/Pages.hs
+++ b/src/PDF/Pages.hs
@@ -8,7 +8,7 @@ module PDF.Pages (
 import Codec.Compression.Zlib (decompress)
 import Control.Applicative ((<|>))
 import Control.Monad (foldM)
-import Control.Monad.RWS (RWST(..), ask, evalRWST, mapRWST, modify)
+import Control.Monad.RWS (RWST(..), ask, evalRWST, lift, modify)
 import qualified Control.Monad.RWS as RWS (get)
 import Data.ByteString (ByteString)
 import qualified Data.ByteString.Lazy as Lazy (fromStrict, toStrict)
@@ -35,15 +35,11 @@ data Page = Page {
 
 infixl 1 \\=
 (\\=) :: T a -> (a -> Either String b) -> T b
-x \\= f = mapRWST ((\(a, s, w) -> (\b -> (b, s, w)) <$> f a) =<<) x
+x \\= f = x >>= lift . f
 
 infixl 1 //=
 (//=) :: Either String a -> (a -> T b) -> T b
-(//=) (Left e) _ = RWST (\_ _ -> Left e)
-(//=) (Right a) f = f a
-
-lift :: Either String a -> T a
-lift x = x //= return
+x //= f = lift x >>= f
 
 expected :: Show a => String -> a -> Either String b
 expected name = Left . printf "Not a %s: %s" name . show