Also, we do fusion on strict structures (e.g. vectors), where you get back O(n) on each fused point. Obviously, it is less of a win on lazy structures than the (pathological) case of strict data, but it is still a win.
-- Don On Tue, May 17, 2011 at 11:07 PM, Ben Lippmeier <b...@ouroborus.net> wrote: > > On 18/05/2011, at 15:55 , Roman Cheplyaka wrote: >> Of course I don't claim that fusion is useless -- just trying to >> understand the problem it solves. Are we saving a few closures and cons >> cells here? > > And thunk allocations, and thunk entries. Entering a thunk costs upwards of > 20 cycles, while performing a single addition should only cost one. Imagine > every thunk entry is a function call. You don't want to call a whole function > just to add two numbers together. > > Those "few closures and cons cells" can be surprisingly expensive when > compared to native ALU instructions on a modern machine. > > Ben. > > > > > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
