[Haskell-beginners] Struggling with integrating standalone function with existing vty based app

I have the following code working fine: https://github.com/leonstafford/pandoctest But struggling in bringing it into this vty based app. I admit to not quite understanding the control flow / IO here and could use some tips as to what I'm doing wrong with this one: https://github.com/leonstafford/cli-rss-reader/blob/feature/pandoc-render-ar... As per the comments, I've tried to understand the existing code, but now just finding myself flailing keys and switching type signatures to no avail. Humbly seeking guidance from above! Cheers, Leon