While writing some multi-core concurrent code I needed more precise control over which thread evaluated particular expressions. The default concurrent types, MVar and Chan, are lazy, and sometimes not suitable. The little package, http://hackage.haskell.org/cgi-bin/hackage-scripts/package/strict-concurrenc... Provies the MVar type, but with strict putMVar by default, and an element-strict Chan type. For some applications, these stricter types can yield improved time and space use. (For others, they can make things worse) The strict channel type in particular seems useful, as it can be used to force worker threads to evaluate to WHNF before returning values to a driver thread. Enjoy, Don