newmana

    ./stack install hprotoc
    ~/.local/bin/hprotoc ./gtfs-realtime.proto

The proto file needed to be hacked in 4 ways:
 * comment out/delete the 'syntax = "proto2";' line.
 * insert line breaks before end curly braces:

          extensions 1000 to 1999;

        }

frasertweedale

{-# LANGUAGE ScopedTypeVariables #-}

class HasMode a where
  mode :: Proxy a -> Mode

instance HasMode 'BrowseMail where                                              
  mode _ = BrowseMail

-- | instantiate this class to specify a valid mode transition
class ModeTransition a b where

frasertweedale

{-# LANGUAGE PolyKinds #-}
{-# LANGUAGE DataKinds #-}

module Poly where

data Mode = Mode1 | Mode2

data Action ctx a = Action

-- | Coerce the phantoms (poly-kinded)