Simpler (slower) version of pandoc-tex2svg.hs, without caching

pandoc-tex2svg.hs

{-# LANGUAGE ScopedTypeVariables #-}

module Main where
import Text.Pandoc.JSON
import Control.Monad (when)
import System.Exit
import System.Process
import System.Directory (findExecutable)
import System.IO (stderr, hPutStrLn)

main :: IO ()
main = toJSONFilter tex2svg

tex2svg :: Inline -> IO Inline
tex2svg (Math mt math) = do
  mbfp <- findExecutable "tex2svg"
  when (mbfp == Nothing) $ do
    hPutStrLn stderr $ "The tex2svg program was not found in the path.\n" ++
        "Install MathJax-node (https://github.com/mathjax/MathJax-node)\n" ++
        "and ensure that tex2svg is in your path."
    exitWith $ ExitFailure 1
  svg <- readProcess "tex2svg" (["--inline" | mt == InlineMath] ++ [math]) ""
  if null svg -- indicates an error -- tex2svg doesn't return error status
     then do
       hPutStrLn stderr $ "Could not convert: " ++ math
       return $ Math mt math
     else return $ RawInline (Format "html") $
               "<span class=\"math " ++
               (if mt == InlineMath then "inline" else "display") ++ "\">" ++
               svg ++ "</span>"
tex2svg il = return il

Based on https://github.com/jgm/pandoc-tex2svg/blob/f415448/pandoc-tex2svg.hs but with caching removed. For jgm/pandoc#3153 — removing the caching so that it's easier to measure how long this takes, for input without repetition.