Re: [Haskell-cafe] IORef vs TVar performance: 6 seconds versus 4 minutes

jsnow:

This seems like it ought to be pretty innocuous, unless the whole list is getting evaluated each time I cons a new entry, or if readTVar or writeTVar are much more expensive than they appear.

For general details on the complexity of IORef, MVar or TVar structures, see Comparing the performance of concurrent linked-list implementations in Haskell (Martin Sulzmann, Edmund S. L. Lam, Simon Marlow) Submitted to DAMP'09, October 2008 http://www.haskell.org/~simonmar/papers/concurrent-data.pdf