Work with a StateT transformator

[KommuSoft]

It would be nice if we can also use a StateT monad transformer when walking through the AST and thus keep track of the section, and update the state based on content that we see when "walking" over the tree.

[jgm]

walkM in Text.Pandoc.Walk works for any monad. So yes, you can use it with a state monad or something else with StateT. Am I missing something in your question?

[KommuSoft]

After rereading, I realized it was missing the most important part: the toJSONFilter which does not seem to allow effectively walk over this.

The implementation looks like

pandoc-types/src/Text/Pandoc/JSON.hs

Lines 120 to 124 in da9aeed

	instance (Walkable [a] Pandoc) => ToJSONFilter (a -> IO [a]) where
	toJSONFilter f = BL.getContents >>=
	(walkM (fmap concat . mapM f) :: Pandoc -> IO Pandoc) .
	either error id . eitherDecode' >>=
	BL.putStr . encode

so probably generalizing it to any monad transformer with IO as the "outer" one is possible. I will take a look into it.

[jgm]

Yes, maybe we could generalize these to any MonadIO instance.
An alternative approach that should work already would be to use the IO Monad and an IORef for state.

[jgm]

Closed by #105.