CODEWITHSUNDEEP
unixocamlsleep
Mark Bukharov
Mark Bukharov

Reputation: 11

How can I make a program wait in OCaml?

I'm trying to make a tetris game in ocaml and i need to have a piece move through the graphics screen at a certain speed. I think that the best way to do it is to make a recursive function that draws the piece at the top of the screen, waits half a second or so, clears that piece from the screen and redraws it 50 pixels lower. I just don't know how to make the programm wait. I think that you can do it using the Unix module but idk how..

Upvotes: 1

Views: 1365

Answers (1)

Jeffrey Scofield
Jeffrey Scofield

Reputation: 66823

Let's assume you want to take a fairly simple approach, i.e., an approach that works without multi-threading.

Presumably when your game is running it spends virtually all its time waiting for input from the user, i.e., waiting for the user to press a key. Most likely, in fact, you're using a blocking read to do this. Since the user can take any amount of time before typing anything (up to minutes or years), this is incompatible with keeping the graphical part of the game up to date.

A very simple solution then is to have a timeout on the read operation. Instead of waiting indefinitely for the user to press a key, you can wait at most (say) 10 milliseconds.

To do this, you can use the Unix.select function. The simplest way to do this is to switch over to using a Unix file descriptor for your input rather than an OCaml channel. If you can't figure out how to make this work, you might come back to StackOverflow with a more specific question.

Upvotes: 1

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