feat: use pandoc-lua-engine

flake.nix

@@ -17,6 +17,20 @@
         haskellProjects.default = {
           packages = {
             tztime.source = "0.1.1.0";  # version in nixpkgs is marked broken
+            #pandoc-lua-engine.source = "0.2.1.5";
+          };
+          settings.nebelhorn = {
+            /*
+            I'm not sure why, but since adding `pandoc-lua-engine` I need to manually remove these
+            packages or otherwise `justStaticExecutables` will lead to an error that the output
+            "is not allowed to refer to the following paths" from ghc.
+            */
+            removeReferencesTo = [
+              pkgs.haskellPackages.pandoc-types
+              pkgs.haskellPackages.pandoc
+              pkgs.haskellPackages.tzdata
+            ];
+            justStaticExecutables = true;
           };
           devShell = {
             mkShellArgs = {
@@ -25,7 +39,7 @@
           };
         };
 
-        packages.default = pkgs.haskell.lib.justStaticExecutables self'.packages.nebelhorn;
+        packages.default = self'.packages.nebelhorn;
         apps.default = self'.apps.nebelhorn;
 
         packages.image = pkgs.dockerTools.buildImage {

nebelhorn.cabal

@@ -44,7 +44,7 @@ executable nebelhorn
     , optparse-applicative
     , pandoc
     , pandoc-types
-    -- pandoc-lua-engine will be needed for pandoc 3
+    , pandoc-lua-engine
     , path
     , path-io
     , process

src/Build.hs

@@ -5,7 +5,7 @@ import Text.Pandoc.Definition
 import Text.Pandoc.Class
 import Text.Pandoc.Options (def)
 import qualified Text.Pandoc.Filter as Filter
-import Text.Pandoc.Scripting (noEngine)
+import Text.Pandoc.Lua (getEngine)
 import Nebelhorn
 import Util
 import Config
@@ -13,7 +13,7 @@ import Save
 import Path
 import Data.List (union)
 import qualified Data.Map as Map (singleton, empty)
-import Control.Concurrent.Async (mapConcurrently)
+import Control.Concurrent.Async (forConcurrently)
 import qualified Data.Text as T
 import Data.Char (isAlphaNum)
 
@@ -187,14 +187,11 @@ putIndex nebelhorn = mapPages putIndex' nebelhorn where
 
 applyFilters :: Nebelhorn -> IO Nebelhorn
 applyFilters nebelhorn@Nebelhorn{..} = do
-    pages' <- (runIOorExplode <$> apply) `mapConcurrently` nebelhornPages
+    engine <- getEngine
+    pages' <- forConcurrently nebelhornPages $ runIOorExplode <$> \page@Page{..} -> do
+        doc' <- Filter.applyFilters engine def nebelhornFilters ["html"] pageDoc
+        return page { pageDoc = doc' }
     return nebelhorn { nebelhornPages = pages' }
-    where
-
-        apply :: (PandocMonad m, MonadIO m) => Page -> m Page
-        apply page@Page{..} = do
-            doc' <- Filter.applyFilters noEngine def nebelhornFilters ["html"] pageDoc
-            return page { pageDoc = doc' }
 
 putFeeds :: Nebelhorn -> Nebelhorn
 putFeeds nebelhorn@Nebelhorn{..} = nebelhorn { nebelhornFeeds = putFeed <$> nebelhornFeeds } where