RE: [Haskell-cafe] Newbie question: mutually exclusive strict / lazy

Yes, sorry, GHC's strictness analyzer. What I meant with this email is that I guess that for a strictness analyzer, the information that a function is strict in an argument *independent from the other arguments* would not be good enough in itself for optimization, it would be better to also use the dependencies between the arguments (as in the case of the if.then.else). It seems one can indicate in GHC that an argument is strict using annotiations, but I don't see a way of specifying these dependencies (maybe this does not make sense, and this is all newbie nonsense). Of course, with whole program optimization this would not be necessary, but if the compiler just sees the function signature, he must assume that a lazy argument is always lazy, independent of the value of other strict arguments no? Cheers, Peter From: lennart.augustsson@gmail.com [mailto:lennart.augustsson@gmail.com] On Behalf Of Lennart Augustsson Sent: maandag 11 februari 2008 0:28 To: Peter Verswyvelen Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] Newbie question: mutually exclusive strict / lazy I'm not sure what you mean by "the strictness analyzer". GHC's strictness analyzer? I don't know, but I would hope so since it was done already in 1980 by Alan Mycroft. -- Lennart On Sat, Feb 9, 2008 at 4:33 PM, Peter Verswyvelen wrote: Consider the function cond x y z = if x then y else z I guess we can certainly say cond is strict in x. But what about y and z? If x is true, then cond is strict in y If x is false, then cond is strict in z So we can't really say cond is lazy nor strict in its second or third argument. Of course, this is the case for many more functions, but in the case of the if-then-else primitive, does the strictness analyzer make use of this "mutually exclusive strictness" fact? Cheers, Peter _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe