-----------------------------------------------------------------------------
-- |
-- Module      :  Main
-- Copyright   :  (c) Brent Yorgey 2011
-- License     :  BSD-style (see LICENSE)
-- Maintainer  :  Brent Yorgey <byorgey@cis.upenn.edu>
-- Stability   :  experimental
--
-- Ott (<http://www.cl.cam.ac.uk/~pes20/ott/>) is a tool for writing
-- formal definitions of programming languages and calculi.  Often the
-- Ott grammars one defines end up being ambiguous, and Ott signals
-- its displeasure by spewing forth several massive parse trees in a
-- format requiring formidable patience to read.  Finding the slight
-- differences between two such parse trees is an exercise in
-- seizure-inducing tedium.
--
-- To the rescue comes ottparse-pretty!  Simply paste in each parse
-- and it is shown to you in a nicely formatted tree form with all the
-- extra meaningless cruft removed.
--
-- For example, it turns this:
--
-- @
-- (St_node :formula:formula_judgement: (Ste_st (St_node :judgement:judgement_Jtype: (Ste_st (St_node :Jtype:coerce: (Ste_st (St_nonterm G)) (Ste_st (St_nonterm g)) (Ste_st (St_node :s:T_MultiTypeApp: (Ste_st (St_node :s:T_EqTy: (Ste_st (St_node :s:T_MultiTypeApp: (Ste_st (St_node :s:T_MultiKindApp: (Ste_st (St_node :s:T_Cons: (Ste_st (St_nonterm H)))) (Ste_st (St_nonterm k)))) (Ste_st (St_nonterm t)))) (Ste_st (St_node :s:T_MultiKindApp: (Ste_st (St_node :s:T_Cons: (Ste_st (St_nonterm H)))) (Ste_st (St_nonterm k)))))) (Ste_st (St_nonterm t')))))))))
-- @
--
-- into this:
--
-- @
-- formula_judgement
-- |
-- `- judgement_Jtype
--    |
--    `- coerce
--       |
--       +- G
--       |
--       +- g
--       |
--       `- T_MultiTypeApp
--          |
--          +- T_EqTy
--          |  |
--          |  +- T_MultiTypeApp
--          |  |  |
--          |  |  +- T_MultiKindApp
--          |  |  |  |
--          |  |  |  +- T_Cons
--          |  |  |  |  |
--          |  |  |  |  `- H
--          |  |  |  |
--          |  |  |  `- k
--          |  |  |
--          |  |  `- t
--          |  |
--          |  `- T_MultiKindApp
--          |     |
--          |     +- T_Cons
--          |     |  |
--          |     |  `- H
--          |     |
--          |     `- k
--          |
--          `- t'
-- @
--
-----------------------------------------------------------------------------
import Text.Ott.Pretty

import System.IO     (hSetBuffering, BufferMode(..), stdout)
import Control.Monad (forever)
import Text.Parsec   (runParser)
import Data.Tree     (drawTree)

main :: IO ()
main = do
  hSetBuffering stdout NoBuffering
  forever interpTree

interpTree :: IO ()
interpTree = do
  putStr "> "
  tStr <- getLine
  case runParser parseTree () "" tStr of
    Left err -> print err
    Right t -> putStr $ drawTree (normalizeTree t)