HLint: use fromMaybe

Replace uses of `maybe x id` with `fromMaybe x`.

src/Text/Pandoc/PDF.hs

@@ -41,6 +41,7 @@ import System.Directory
 import System.Environment
 import Control.Monad (unless)
 import Data.List (isInfixOf)
+import Data.Maybe (fromMaybe)
 import qualified Data.ByteString.Base64 as B64
 import qualified Text.Pandoc.UTF8 as UTF8
 import Text.Pandoc.Definition
@@ -87,7 +88,7 @@ handleImage' baseURL tmpdir (Image ils (src,tit)) = do
          res <- fetchItem baseURL src
          case res of
               Right (contents, Just mime) -> do
-                let ext = maybe (takeExtension src) id $
+                let ext = fromMaybe (takeExtension src) $
                           extensionFromMimeType mime
                 let basename = UTF8.toString $ B64.encode $ UTF8.fromString src
                 let fname = tmpdir </> basename <.> ext

src/Text/Pandoc/Readers/DocBook.hs

@@ -12,6 +12,7 @@ import Data.Char (isSpace)
 import Control.Monad.State
 import Control.Applicative ((<$>))
 import Data.List (intersperse)
+import Data.Maybe (fromMaybe)
 
 {-
 
@@ -683,7 +684,7 @@ parseBlock (Elem e) =
                                "lowerroman" -> LowerRoman
                                "upperroman" -> UpperRoman
                                _            -> Decimal
-          let start = maybe 1 id $
+          let start = fromMaybe 1 $
                       (attrValue "override" <$> filterElement (named "listitem") e)
                        >>= safeRead
           orderedListWith (start,listStyle,DefaultDelim)
@@ -779,7 +780,7 @@ parseBlock (Elem e) =
                       caption <- case filterChild isCaption e of
                                        Just t  -> getInlines t
                                        Nothing -> return mempty
-                      let e' = maybe e id $ filterChild (named "tgroup") e
+                      let e' = fromMaybe e $ filterChild (named "tgroup") e
                       let isColspec x = named "colspec" x || named "col" x
                       let colspecs = case filterChild (named "colgroup") e' of
                                            Just c -> filterChildren isColspec c
@@ -801,7 +802,7 @@ parseBlock (Elem e) =
                                                 Just "center" -> AlignCenter
                                                 _             -> AlignDefault
                       let toWidth c = case findAttr (unqual "colwidth") c of
-                                                Just w -> maybe 0 id
+                                                Just w -> fromMaybe 0
                                                    $ safeRead $ '0': filter (\x ->
                                                      (x >= '0' && x <= '9')
                                                       || x == '.') w

src/Text/Pandoc/Readers/HTML.hs

@@ -207,7 +207,7 @@ pHeader = try $ do
   let bodyTitle = TagOpen tagtype attr ~== TagOpen "h1" [("class","title")]
   let level = read (drop 1 tagtype)
   contents <- liftM concat $ manyTill inline (pCloses tagtype <|> eof)
-  let ident = maybe "" id $ lookup "id" attr
+  let ident = fromMaybe "" $ lookup "id" attr
   let classes = maybe [] words $ lookup "class" attr
   let keyvals = [(k,v) | (k,v) <- attr, k /= "class", k /= "id"]
   return $ if bodyTitle
@@ -257,7 +257,7 @@ pCol = try $ do
   skipMany pBlank
   return $ case lookup "width" attribs of
            Just x | not (null x) && last x == '%' ->
-             maybe 0.0 id $ safeRead ('0':'.':init x)
+             fromMaybe 0.0 $ safeRead ('0':'.':init x)
            _ -> 0.0
 
 pColgroup :: TagParser [Double]

src/Text/Pandoc/Readers/Markdown.hs

@@ -1722,7 +1722,7 @@ spanHtml = try $ do
   guardEnabled Ext_markdown_in_html_blocks
   (TagOpen _ attrs, _) <- htmlTag (~== TagOpen "span" [])
   contents <- mconcat <$> manyTill inline (htmlTag (~== TagClose "span"))
-  let ident = maybe "" id $ lookup "id" attrs
+  let ident = fromMaybe "" $ lookup "id" attrs
   let classes = maybe [] words $ lookup "class" attrs
   let keyvals = [(k,v) | (k,v) <- attrs, k /= "id" && k /= "class"]
   return $ B.spanWith (ident, classes, keyvals) <$> contents
@@ -1732,7 +1732,7 @@ divHtml = try $ do
   guardEnabled Ext_markdown_in_html_blocks
   (TagOpen _ attrs, _) <- htmlTag (~== TagOpen "div" [])
   contents <- mconcat <$> manyTill block (htmlTag (~== TagClose "div"))
-  let ident = maybe "" id $ lookup "id" attrs
+  let ident = fromMaybe "" $ lookup "id" attrs
   let classes = maybe [] words $ lookup "class" attrs
   let keyvals = [(k,v) | (k,v) <- attrs, k /= "id" && k /= "class"]
   return $ B.divWith (ident, classes, keyvals) <$> contents

src/Text/Pandoc/Readers/MediaWiki.hs

@@ -54,6 +54,7 @@ import Data.Sequence (viewl, ViewL(..), (<|))
 import qualified Data.Foldable as F
 import qualified Data.Map as M
 import Data.Char (isDigit, isSpace)
+import Data.Maybe (fromMaybe)
 
 -- | Read mediawiki from an input string and return a Pandoc document.
 readMediaWiki :: ReaderOptions -- ^ Reader options
@@ -204,7 +205,7 @@ table = do
   tableStart
   styles <- option [] parseAttrs <* blankline
   let tableWidth = case lookup "width" styles of
-                         Just w  -> maybe 1.0 id $ parseWidth w
+                         Just w  -> fromMaybe 1.0 $ parseWidth w
                          Nothing -> 1.0
   caption <- option mempty tableCaption
   optional rowsep
@@ -285,7 +286,7 @@ tableCell = try $ do
                     Just "center" -> AlignCenter
                     _             -> AlignDefault
   let width = case lookup "width" attrs of
-                    Just xs -> maybe 0.0 id $ parseWidth xs
+                    Just xs -> fromMaybe 0.0 $ parseWidth xs
                     Nothing -> 0.0
   return ((align, width), bs)
 
@@ -387,7 +388,7 @@ orderedList =
           spaces
           items <- many (listItem '#' <|> li)
           optional (htmlTag (~== TagClose "ol"))
-          let start = maybe 1 id $ safeRead $ fromAttrib "start" tag
+          let start = fromMaybe 1 $ safeRead $ fromAttrib "start" tag
           return $ B.orderedListWith (start, DefaultStyle, DefaultDelim) items
 
 definitionList :: MWParser Blocks

src/Text/Pandoc/Writers/Docx.hs

@@ -29,6 +29,7 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Conversion of 'Pandoc' documents to docx.
 -}
 module Text.Pandoc.Writers.Docx ( writeDocx ) where
+import Data.Maybe (fromMaybe)
 import Data.List ( intercalate, groupBy )
 import qualified Data.ByteString as B
 import qualified Data.ByteString.Lazy as BL
@@ -130,7 +131,8 @@ writeDocx opts doc@(Pandoc meta _) = do
   let mkOverrideNode (part', contentType') = mknode "Override"
                [("PartName",part'),("ContentType",contentType')] ()
   let mkImageOverride (_, imgpath, mbMimeType, _, _) =
-             mkOverrideNode ("/word/" ++ imgpath, maybe "application/octet-stream" id mbMimeType)
+             mkOverrideNode ("/word/" ++ imgpath,
+                             fromMaybe "application/octet-stream" mbMimeType)
   let overrides = map mkOverrideNode
                   [("/word/webSettings.xml",
                     "application/vnd.openxmlformats-officedocument.wordprocessingml.webSettings+xml")
@@ -322,7 +324,7 @@ mkNum markers marker numid =
        NumberMarker _ _ start ->
           map (\lvl -> mknode "w:lvlOverride" [("w:ilvl",show (lvl :: Int))]
               $ mknode "w:startOverride" [("w:val",show start)] ()) [0..6]
-   where absnumid = maybe 0 id $ M.lookup marker markers
+   where absnumid = fromMaybe 0 $ M.lookup marker markers
 
 mkAbstractNum :: (ListMarker,Int) -> IO Element
 mkAbstractNum (marker,numid) = do

src/Text/Pandoc/Writers/EPUB.hs

@@ -176,7 +176,7 @@ addMetadataFromXML e@(Element (QName name _ (Just "dc")) attrs _ _) md
                  , titleFileAs = getAttr "file-as"
                  , titleType = getAttr "type"
                  } : epubTitle md }
-  | name == "date" = md{ epubDate = maybe "" id $ normalizeDate'
+  | name == "date" = md{ epubDate = fromMaybe "" $ normalizeDate'
                                                  $ strContent e }
   | name == "language" = md{ epubLanguage = strContent e }
   | name == "creator" = md{ epubCreator =
@@ -271,7 +271,7 @@ metadataFromMeta opts meta = EPUBMetadata{
     }
   where identifiers = getIdentifier meta
         titles = getTitle meta
-        date = maybe "" id $
+        date = fromMaybe "" $
               (metaValueToString <$> lookupMeta "date" meta) >>= normalizeDate'
         language = maybe "" metaValueToString $
            lookupMeta "language" meta `mplus` lookupMeta "lang" meta
@@ -297,7 +297,7 @@ writeEPUB :: WriterOptions  -- ^ Writer options
           -> Pandoc         -- ^ Document to convert
           -> IO B.ByteString
 writeEPUB opts doc@(Pandoc meta _) = do
-  let version = maybe EPUB2 id (writerEpubVersion opts)
+  let version = fromMaybe EPUB2 (writerEpubVersion opts)
   let epub3 = version == EPUB3
   epochtime <- floor `fmap` getPOSIXTime
   let mkEntry path content = toEntry path epochtime content
@@ -401,7 +401,7 @@ writeEPUB opts doc@(Pandoc meta _) = do
       chapToEntry num (Chapter mbnum bs) = mkEntry (showChapter num)
         $ renderHtml
         $ writeHtml opts'{ writerNumberOffset =
-            maybe [] id mbnum }
+            fromMaybe [] mbnum }
         $ case bs of
               (Header _ _ xs : _) ->
                  Pandoc (setMeta "title" (fromList xs) nullMeta) bs
@@ -436,7 +436,7 @@ writeEPUB opts doc@(Pandoc meta _) = do
   let fontNode ent = unode "item" !
                            [("id", takeBaseName $ eRelativePath ent),
                             ("href", eRelativePath ent),
-                            ("media-type", maybe "" id $ getMimeType $ eRelativePath ent)] $ ()
+                            ("media-type", fromMaybe "" $ getMimeType $ eRelativePath ent)] $ ()
   let plainTitle = case docTitle meta of
                         [] -> case epubTitle metadata of
                                    []   -> "UNTITLED"

src/Text/Pandoc/Writers/HTML.hs

@@ -45,7 +45,7 @@ import Numeric ( showHex )
 import Data.Char ( ord, toLower )
 import Data.List ( isPrefixOf, intersperse )
 import Data.String ( fromString )
-import Data.Maybe ( catMaybes )
+import Data.Maybe ( catMaybes, fromMaybe )
 import Control.Monad.State
 import Text.Blaze.Html hiding(contents)
 import Text.Blaze.Internal(preEscapedString)
@@ -118,7 +118,7 @@ pandocToHtml opts (Pandoc meta blocks) = do
   let stringifyHTML = escapeStringForXML . stringify
   let authsMeta = map stringifyHTML $ docAuthors meta
   let dateMeta  = stringifyHTML $ docDate meta
-  let slideLevel = maybe (getSlideLevel blocks) id $ writerSlideLevel opts
+  let slideLevel = fromMaybe (getSlideLevel blocks) $ writerSlideLevel opts
   let sects = hierarchicalize $
               if writerSlideVariant opts == NoSlides
                  then blocks

src/Text/Pandoc/Writers/LaTeX.hs

@@ -40,6 +40,7 @@ import Network.URI ( isURI, unEscapeString )
 import Data.List ( (\\), isSuffixOf, isInfixOf,
                    isPrefixOf, intercalate, intersperse )
 import Data.Char ( toLower, isPunctuation, isAscii, isLetter, isDigit, ord )
+import Data.Maybe ( fromMaybe )
 import Control.Applicative ((<|>))
 import Control.Monad.State
 import Text.Pandoc.Pretty
@@ -240,7 +241,7 @@ inCmd cmd contents = char '\\' <> text cmd <> braces contents
 toSlides :: [Block] -> State WriterState [Block]
 toSlides bs = do
   opts <- gets stOptions
-  let slideLevel = maybe (getSlideLevel bs) id $ writerSlideLevel opts
+  let slideLevel = fromMaybe (getSlideLevel bs) $ writerSlideLevel opts
   let bs' = prepSlides slideLevel bs
   concat `fmap` (mapM (elementToBeamer slideLevel) $ hierarchicalize bs')
 

src/Text/Pandoc/Writers/ODT.hs

@@ -31,6 +31,7 @@ Conversion of 'Pandoc' documents to ODT.
 module Text.Pandoc.Writers.ODT ( writeODT ) where
 import Data.IORef
 import Data.List ( isPrefixOf )
+import Data.Maybe ( fromMaybe )
 import qualified Data.ByteString.Lazy as B
 import Text.Pandoc.UTF8 ( fromStringLazy )
 import Codec.Archive.Zip
@@ -127,7 +128,7 @@ transformPic opts entriesRef (Image lab (src,_)) = do
        return $ Emph lab
      Right (img, _) -> do
        let size = imageSize img
-       let (w,h) = maybe (0,0) id $ sizeInPoints `fmap` size
+       let (w,h) = fromMaybe (0,0) $ sizeInPoints `fmap` size
        let tit' = show w ++ "x" ++ show h
        entries <- readIORef entriesRef
        let newsrc = "Pictures/" ++ show (length entries) ++ takeExtension src