#!/usr/bin/env stack
{- stack script
   --resolver lts-11.6
   --install-ghc
   --package protolude
-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# LANGUAGE OverloadedStrings #-}
import Protolude

guess :: IO ()
guess = guessBetween 0 120

guessBetween :: Integer -> Integer -> IO ()
guessBetween minAge maxAge = do
  let age = (maxAge + minAge) `div` 2
  if minAge == maxAge
    then putText ("You are " <> show minAge)
    else do
      putText ("Are you younger than " <> show age <> "?")
      answer <- getLine
      case answer of
        "y" -> guessBetween minAge (age - 1)
        _ ->  guessBetween (if age == minAge then age + 1 else age) maxAge

main :: IO ()
main = do
  guess
  putText "Thanks for playing!"