Re: [Haskell-beginners] How to display a time difference?

Colin Paul Adams wrote:

The code of the following routine is intended to indicate how long it takes for the computer to make a move. However the time is printed (as very close to zero) long before the move is made.

You are writing a thunk to the IORef. It only gets computed later on when you read the value. Try using:

readIORef game_state_ior >>= evaluate . update_interactive_from_move move >>= writeIORef game_state_ior

evaluate is in Control.Exception. -Yitz