Converting `Dialogue' I/O

1. The type `Dialogue' usually can become `IO ()'.
2. Change `readChan stdin' to `getContents'.
3. Change `appendChan stdout' to `putStr', which is equivalent to `hPutStr stdout'. Change `appendChan stderr' to `hPutStr stderr'.
4. You need to `import IO' to do any interesting I/O; in particular, anything to do with `Handle's.
5. You need to `import System' if you used `getArgs', `getEnv', or `getProgName'.
6. Assuming continuation-style `Dialogue' code, change `... exit done $' to `... >>'. Change `... exit $ \ foo ->' to `... >>= \ foo ->'.
7. Sometimes, when you change your `main' routine to "do" notation, you'll get an error message like:

   "Main.hs", line 32: No instance for: Prelude.MonadZero IO
       "Main.hs", line 32: in a do statement
   

   This probably means that you need to "twiddle" some patterns; e.g., I added the twiddle to the `getArgs'-related pattern here:

   main = do
       ~[a1] <- getArgs
       let x = fst (head ((reads::ReadS Int) a1)
       putStr (show (result x))
   

8. If you had any functions named `(>>)', `(>>=)', or `return', change them to something else.
9. If you used the `StatusFile' I/O request, do something else. No exact equivalent exists in 1.3.