Provide IO a -> Canvas a

[nomeata]

This is obviously not something to be exported by the main module, but for some tasks, it is necessary to do (local) IO in the Canvas monad.

Would it be possible to implement ioToCanvas :: IO a -> Canvas a, exported via some .Internal module maybe?

[nomeata]

Things I want to do here are:

• Waiting for a certain amount of time
• Getting the current time
• Reading and writing MVars

The former two might not be needed if #18 is implemented, but in general, there is always a chance that something is missing from a too-abstract interface.

[nomeata]

Nevermind, I think I am being stupid here.

[andygill]

We had this at some point. There are pros and cons. We decided to remove it, because it clarifies what Canvas can actually do - talk to the browser.