tricu/src/REPL.hs

module REPL where

import Eval
import Lexer
import Parser
import Research

import Control.Monad         (void)
import qualified Data.Map as Map
import System.IO            (hFlush, stdout)

repl :: Map.Map String T -> IO ()
repl env = do
  putStr "sapling < "
  hFlush stdout
  input <- getLine
  if input == "_:exit"
    then putStrLn "Goodbye!"
  else if input == ""
    then do
      putStrLn ""
      repl env
    else do
      let clearEnv = Map.delete "__result" env
      let newEnv   = evalSingle clearEnv (parseSingle input)
      case Map.lookup "__result" newEnv of
        Just r  -> do
          putStrLn $ "sapling > " ++ show r
          putStrLn $ "DECODE -: " ++ (decodeResult r)
        Nothing -> pure ()
      repl newEnv

decodeResult :: T -> String
decodeResult tc = 
  case ofString tc of
    Right str -> "\"" ++ str ++ "\""
    Left _ -> case ofNumber tc of
      Right num -> "# " ++ show num
      Left _ -> "Failed to decode number from Tree"