On Thu, Apr 12, 2012 at 6:22 PM, Antoine Latter <aslat...@gmail.com> wrote: > Hi Warren, > > On Thu, Apr 12, 2012 at 6:31 PM, Warren Harris <warrensomeb...@gmail.com> > wrote: >> I wrote a parsec parser that does symbols lookups during the parsing process >> (ParsecT String Store IO a). Now I'd like to write a pretty printer that >> does the reverse. Unfortunately there doesn't appear to be a transformer >> version of Text.PrettyPrint.HughesPJ. Can anyone suggest a way to do this? >> Thanks, > > It seems like the opposite would be a function of type 'a -> Store -> IO Doc'. > > Maybe a function of type 'a -> ReaderT Store IO Doc' could be easier > to work with. > > If you go this route you could write a lifted versions of (<>), (<+>), hcat > etc. > > An example: > > (<>) :: Applicative m => m Doc -> m Doc -> m Doc
On this note, there are various Wadler-Leijin pretty printers variants on hackage, some lifted into a monad so you can do effects, IO, or whatever. E.g. wl-pprint-extras. In my experience though WL gives worse results than H-PJ despite having some more powerful operators. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
