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authorJasper Van der Jeugt <jaspervdj@gmail.com>2017-11-21 18:20:05 +0100
committerJohn MacFarlane <jgm@berkeley.edu>2017-11-21 09:20:05 -0800
commit30c1e53c42b4829c6eac9ab55d66fac6411c2c71 (patch)
treedab64804040f8972644db57c0b66ada10e42d30b /src/Text/Pandoc
parent185918ea3d5ad759d7050e8ccb638734231e6762 (diff)
downloadpandoc-30c1e53c42b4829c6eac9ab55d66fac6411c2c71.tar.gz
Change JSON instances for Opt to TemplateHaskell (#4083)
The `Generic` JSON instances for `Text.Pandoc.App.Opt` seem to tickle a particulary bad quadratic complexity case (Generics complexity is worse than quadratic with respect to the number of fields in the datatype). This is with GHC-8.2.1, I didn't test it using 8.0 but I assume it is similar. Using `Generic`, compilation of the `Text.Pandoc.App` module takes minutes and often gets killed due to out of memory on slower machines with "only" 8GB of accessible memory. This is particularly annoying to me since it means I cannot build pandoc on Travis. TemplateHaskell is a little uglier, but the module seems to compile within a few seconds, and compilation doesn't take more than 1GB of memory. Should I also change the other JSON instances throughout the codebase for consistency?
Diffstat (limited to 'src/Text/Pandoc')
-rw-r--r--src/Text/Pandoc/App.hs16
1 files changed, 6 insertions, 10 deletions
diff --git a/src/Text/Pandoc/App.hs b/src/Text/Pandoc/App.hs
index d9f92335c..4c4525dce 100644
--- a/src/Text/Pandoc/App.hs
+++ b/src/Text/Pandoc/App.hs
@@ -1,6 +1,7 @@
{-# LANGUAGE CPP #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TemplateHaskell #-}
{-# LANGUAGE TupleSections #-}
{-
Copyright (C) 2006-2017 John MacFarlane <jgm@berkeley.edu>
@@ -44,8 +45,8 @@ import qualified Control.Exception as E
import Control.Monad
import Control.Monad.Except (catchError, throwError)
import Control.Monad.Trans
-import Data.Aeson (FromJSON (..), ToJSON (..), defaultOptions, eitherDecode',
- encode, genericToEncoding)
+import Data.Aeson (defaultOptions, eitherDecode', encode)
+import Data.Aeson.TH (deriveJSON)
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as B
import Data.Char (toLower, toUpper)
@@ -95,10 +96,6 @@ import System.Posix.Terminal (queryTerminal)
data LineEnding = LF | CRLF | Native deriving (Show, Generic)
-instance ToJSON LineEnding where
- toEncoding = genericToEncoding defaultOptions
-instance FromJSON LineEnding
-
parseOptions :: [OptDescr (Opt -> IO Opt)] -> Opt -> IO Opt
parseOptions options' defaults = do
rawArgs <- map UTF8.decodeArg <$> getArgs
@@ -646,10 +643,6 @@ data Opt = Opt
, optStripComments :: Bool -- ^ Skip HTML comments
} deriving (Generic, Show)
-instance ToJSON Opt where
- toEncoding = genericToEncoding defaultOptions
-instance FromJSON Opt
-
-- | Defaults for command-line options.
defaultOpts :: Opt
defaultOpts = Opt
@@ -1677,3 +1670,6 @@ deprecatedOption o =
\r -> case r of
Right () -> return ()
Left e -> E.throwIO e
+
+$(deriveJSON defaultOptions ''LineEnding)
+$(deriveJSON defaultOptions ''Opt)