On Wed, 2009-03-04 at 18:22 -0800, Jonathan Cast wrote: > On Wed, 2009-03-04 at 18:12 -0800, o...@okmij.org wrote: > > > > We demonstrate how lazy IO breaks referential transparency. A pure > > function of the type Int->Int->Int gives different integers depending > > on the order of evaluation of its arguments. Our Haskell98 code uses > > nothing but the standard input. We conclude that extolling the purity > > of Haskell and advertising lazy IO is inconsistent.
> ... > > Running the code with Hugs exhibits the same behavior. Thus a pure > > function (-) of the pure type gives different results depending on the > > order of evaluating its arguments. > > > > Is 1 = -1? > > Lazy IO *as implemented (originally) in GHC* (and copied into the > Haskell standard) breaks referential transparency.[1] Clean's object IO > system, I believe, would not have this problem. Nor would a > well-designed Haskell IO system. jcc [1] Oops, ignore this reference. I decided against saying what I was going to here. _______________________________________________ Haskell mailing list Haskell@haskell.org http://www.haskell.org/mailman/listinfo/haskell
