From 7fa5fbed9e0440694e9c52a8dc83f3e4f29c8a96 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Thu, 28 Mar 2019 13:51:15 -0700
Subject: [PATCH] Use strict instead of lazy sum.
sum is lazy; replace with `foldl' (+) 0` to avoid stack
overflow in Text.Pandoc.Pretty with very long strings.
Closes #5401.
---
src/Text/Pandoc/Pretty.hs | 6 +++---
src/Text/Pandoc/Writers/Shared.hs | 4 ++--
2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/src/Text/Pandoc/Pretty.hs b/src/Text/Pandoc/Pretty.hs
index 2d7a3a725..ad223274e 100644
--- a/src/Text/Pandoc/Pretty.hs
+++ b/src/Text/Pandoc/Pretty.hs
@@ -65,7 +65,7 @@ import Control.Monad
import Control.Monad.State.Strict
import Data.Char (isSpace)
import Data.Foldable (toList)
-import Data.List (intersperse)
+import Data.List (intersperse, foldl')
import Data.Sequence (Seq, ViewL (..), fromList, mapWithIndex, singleton, viewl,
(<|))
import qualified Data.Sequence as Seq
@@ -305,7 +305,7 @@ renderList (BreakingSpace : xs) = do
let xs' = dropWhile isBreakingSpace xs
let next = takeWhile isText xs'
st <- get
- let off = sum $ map offsetOf next
+ let off = foldl' (+) 0 $ map offsetOf next
case lineLength st of
Just l | column st + 1 + off > l -> do
outp (-1) "\n"
@@ -540,4 +540,4 @@ charWidth c =
-- | Get real length of string, taking into account combining and double-wide
-- characters.
realLength :: String -> Int
-realLength = sum . map charWidth
+realLength = foldl' (+) 0 . map charWidth
diff --git a/src/Text/Pandoc/Writers/Shared.hs b/src/Text/Pandoc/Writers/Shared.hs
index 7027a9576..f4370b7bf 100644
--- a/src/Text/Pandoc/Writers/Shared.hs
+++ b/src/Text/Pandoc/Writers/Shared.hs
@@ -41,7 +41,7 @@ import Data.Aeson (FromJSON (..), Result (..), ToJSON (..), Value (Object),
encode, fromJSON)
import Data.Char (chr, ord, isSpace, isDigit)
import qualified Data.HashMap.Strict as H
-import Data.List (groupBy, intersperse, transpose)
+import Data.List (groupBy, intersperse, transpose, foldl')
import qualified Data.Map as M
import Data.Maybe (isJust)
import qualified Data.Text as T
@@ -279,7 +279,7 @@ gridTable opts blocksToDoc headless aligns widths headers rows = do
-- handleGivenWidths
let handleZeroWidths = do
(widthsInChars', rawHeaders', rawRows') <- handleFullWidths
- if sum widthsInChars' > writerColumns opts
+ if foldl' (+) 0 widthsInChars' > writerColumns opts
then -- use even widths
handleGivenWidths
(replicate numcols (1.0 / fromIntegral numcols) :: [Double])