Miscellaneous refactors

src/Text/Pandoc/App/OutputSettings.hs

@@ -29,7 +29,7 @@ import Control.Monad.Except (throwError)
 import Control.Monad.Trans
 import Data.Char (toLower)
 import Data.List (find)
-import Data.Maybe (fromMaybe)
+import Data.Maybe (catMaybes, fromMaybe)
 import Skylighting (defaultSyntaxMap)
 import Skylighting.Parser (addSyntaxDefinition, parseSyntaxDefinition)
 import System.Directory (getCurrentDirectory)
@@ -321,10 +321,11 @@ isBinaryFormat s =
 sandbox' :: (PandocMonad m, MonadIO m) => Opt -> PandocPure a -> m a
 sandbox' opts = sandbox sandboxedFiles
  where
-   sandboxedFiles = maybe id (:) (optReferenceDoc opts) .
-                    maybe id (:) (optEpubMetadata opts) .
-                    maybe id (:) (optEpubCoverImage opts) .
-                    maybe id (:) (optCSL opts) .
-                    maybe id (:) (optCitationAbbreviations opts) $
+   sandboxedFiles = catMaybes [ optReferenceDoc opts
+                              , optEpubMetadata opts
+                              , optEpubCoverImage opts
+                              , optCSL opts
+                              , optCitationAbbreviations opts
+                              ] ++
                     optEpubFonts opts ++
                     optBibliography opts

src/Text/Pandoc/Readers/HTML.hs

@@ -927,25 +927,21 @@ pMath inCase = try $ do
   let attr = toStringAttr attr'
   unless inCase $
     guard (maybe True (== mathMLNamespace) (lookup "xmlns" attr))
-  let isDisplay = case lookup "display" attr of
-                     Just "block" -> True
-                     _ -> False
+  let constructor = case lookup "display" attr of
+                       Just "block" -> B.displayMath
+                       _ -> B.math
   contents <- manyTill pAny (pSatisfy (matchTagClose "math"))
   -- KaTeX and others include original TeX in annotation tag;
   -- just use this if present rather than parsing MathML:
   case extractTeXAnnotation contents of
-    Just x -> return $ if isDisplay
-                          then B.displayMath x
-                          else B.math x
+    Just x -> return $ constructor x
     Nothing ->
       case mathMLToTeXMath (renderTags $
               [open] <> contents <> [TagClose "math"]) of
            Left _   -> return $ B.spanWith ("",["math"],attr) $ B.text $
                                  innerText contents
            Right "" -> return mempty
-           Right x  -> return $ if isDisplay
-                                   then B.displayMath x
-                                   else B.math x
+           Right x  -> return $ constructor x
 
 extractTeXAnnotation :: [Tag Text] -> Maybe Text
 extractTeXAnnotation [] = Nothing

src/Text/Pandoc/Readers/Mdoc.hs

@@ -26,7 +26,7 @@ import Control.Monad.Except (throwError)
 #if MIN_VERSION_base(4,19,0)
 import Data.List (intersperse, unsnoc)
 #else
-import Data.List (intersperse, uncons)
+import Data.List (intersperse)
 #endif
 import qualified Data.Map.Strict as M
 import qualified Data.Text as T
@@ -46,7 +46,7 @@ import Text.Pandoc.Shared (stringify)
 
 #if !MIN_VERSION_base(4,19,0)
 unsnoc :: [a] -> Maybe ([a], a)
-unsnoc xs = (\(hd, tl) -> (reverse tl, hd)) <$> uncons (reverse xs)
+unsnoc = foldr (\x -> Just . maybe ([], x) (\(~(a, b)) -> (x : a, b))) Nothing
 #endif
 
   {- As a general principle, if mandoc -T lint issues a WARNING admonition

src/Text/Pandoc/Readers/Vimwiki.hs

@@ -54,6 +54,7 @@ import Data.List (isInfixOf)
 import Data.Maybe
 import Data.Text (Text)
 import qualified Data.Text as T
+import Safe (lastMay)
 import Text.Pandoc.Builder (Blocks, Inlines, fromList, toList, trimInlines)
 import qualified Text.Pandoc.Builder as B (blockQuote, bulletList, code,
                                            codeBlockWith, definitionList,
@@ -510,9 +511,7 @@ strong = try $ do
   notFollowedBy (oneOf spaceChars)
   contents <- mconcat <$> many1Till inline'
                            (try (char '*' *> notFollowedBy alphaNum))
-  guard $ case reverse (toList contents) of
-             Space:_ -> False
-             _ -> True
+  guard $ lastMay (toList contents) /= Just Space
   return $ B.spanWith (makeId contents, [], []) mempty <> B.strong contents
 
 makeId :: Inlines -> Text
@@ -524,9 +523,7 @@ emph = try $ do
   notFollowedBy (oneOf spaceChars)
   contents <- mconcat <$> many1Till inline'
                            (try (char '_' *> notFollowedBy alphaNum))
-  guard $ case reverse (toList contents) of
-             Space:_ -> False
-             _ -> True
+  guard $ lastMay (toList contents) /= Just Space
   return $ B.emph contents
 
 strikeout :: PandocMonad m => VwParser m Inlines

src/Text/Pandoc/Shared.hs

@@ -523,7 +523,7 @@ makeSectionsWithOffsets numoffsets numbering mbBaseLevel bs =
  where
   getLevel (Header level _ _) = Min level
   getLevel _ = Min 99
-  minLevel = if null numoffsets || all (== 0) numoffsets
+  minLevel = if all (== 0) numoffsets
                 then getMin $ query getLevel bs
                 else 1 -- see #5071, for backwards compatibility
   go :: [Block] -> S.State [Int] [Block]

src/Text/Pandoc/Writers/ANSI.hs

@@ -82,7 +82,7 @@ pandocToANSI opts (Pandoc meta blocks) = do
   body <- blockListToANSI opts blocks'
   notes <- gets $ reverse . stNotes
   let notemark x = D.literal (tshow (x :: Int) <> ".") <+> D.space
-  let marks = take (length notes) $ map notemark [1..]
+  let marks = map notemark [1..length notes]
   let hangWidth = foldr (max . D.offset) 0 marks
   let notepretty | not (null notes) = D.cblock width hr $+$ hangMarks hangWidth marks notes
                  | otherwise = D.empty
@@ -297,12 +297,12 @@ inlineToANSI opts (Strikeout lst) = do
 inlineToANSI opts (Superscript lst) = do
   case traverse toSuperscriptInline lst of
     Just xs -> inlineListToANSI opts xs
-    Nothing -> inlineListToANSI opts lst >>= return . D.parens
+    Nothing -> D.parens <$> inlineListToANSI opts lst
 
 inlineToANSI opts (Subscript lst) = do
   case traverse toSubscriptInline lst of
     Just xs -> inlineListToANSI opts xs
-    Nothing -> inlineListToANSI opts lst >>= return . D.parens
+    Nothing -> D.parens <$> inlineListToANSI opts lst
 
 inlineToANSI opts (SmallCaps lst) = inlineListToANSI opts lst