Duncan Coutts <[EMAIL PROTECTED]> writes: > On Sun, 2006-07-30 at 10:56 +0100, Jón Fairbairn wrote: > > "David House" <[EMAIL PROTECTED]> writes: > > > 1) f is strict iff f _|_ = _|_. > > > 2) f is strict iff it forces evaluation of its arguments. > > > > In (2), you have to be evaluating f on an argument before f > > can force the argument. If you evaluate id x, you > > necessarily evaluate x. I don't think (2) is a very good > > definition, since I don't know what "forces" means here. > > Surely it just means evaluate to weak head normal form?
Means [what] evaluate[s] to whnf? id doesn't do any evaluating, in fact functions in general don't do any evaluating. > Definition 2) relies on following a certain evaluation strategy: that > operationally, functions always return results in weak head normal form. > GHC follows this strategy. It's possibly to imagine returning thunks and > then getting the caller to force the evaluation to WHNF. Which is pretty much my point. Use a definition of "strict" that doesn't depend on anything but denotations (or Böhm trees). -- Jón Fairbairn [EMAIL PROTECTED] _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
