On 02/09/2013 10:50 AM, Johan Holmquist wrote: > I guess I fall more to the "reason about code" side of the scale > rather than "testing the code" side. Testing seem to induce false > hopes about finding all defects even to the point where the tester is > blamed for not finding a bug rather than the developer for introducing > it.
Oh, I'm definitely also on that side, but you have to do the best you can with the tools you have :). > > [Bardur] >> It's definitely a valid point, but isn't that an argument *for* testing >> for preformance regressions rather than *against* compiler optimizations? > > We could test for regressions and pass. Then upgrade to a new version > of compiler and test would no longer pass. And vice versa. > Maybe that's your point too. :) > Indeed :). > [Iustin] >> Surely there will be a canary >> period, parallel running of the old and new system, etc.? > > Is that common? I have not seen it and I do think my workplace is a > rather typical one. I don't know about "common", but I've seen it done a few times. However, it's mostly been in situations where major subsystems have been rewritten and you _really_ want to make sure things still work as they should in production. Sometimes you can get away with just making the new-and-shiny code path a configure-time option and keeping the old-and-beaten code path. (Tends to be messy code-wise until you can excise the old code path, but what're you gonna do?) > > Also, would we really want to preserve the old "bad" code just because > it happened to trigger some optimization? These things depend a lot on the situation at hand -- if it's something 99% of your users will hit, then yes, probably... until you can figure out why the new-and-shiny code *doesn't* get optimized appropriately. > > Don't get me wrong, I am all for compiler optimizations and the > benefits they bring as well as testing. Just highlighting some > potential downsides. > It's all tradeoffs :). Regards, _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe