[Haskell-cafe] Interesting data structure

Paul Johnson paul at cogito.org.uk
Sat Dec 29 02:56:02 EST 2007

Tim Docker wrote:
> I found it worthwhile to try and visualise what's going on here. Let's
> say I have 4 calculations that I want to run in parallel. The first
> doesn't need a request; the second needs to make a single request
> (A1); the third needs to make two requests where the second (B2)
> depends on the result of the first (B1), etc. The resulting parallel
> operations will be done in 3 batches, looking like:
This sounds similar to "futures", where a request for a parallel 
computation returns immediately, but the "value" returned is just a 
placeholder for the result, which will be filled in when it becomes 


More information about the Haskell-Cafe mailing list