--- On Sun, 1/31/10, Steven D'Aprano <ste...@remove.this.cybersource.com.au> wrote:
> From: Steven D'Aprano <ste...@remove.this.cybersource.com.au> > Subject: Re: Python and Ruby > To: python-list@python.org > Date: Sunday, January 31, 2010, 8:22 PM > On Sun, 31 Jan 2010 16:50:50 -0800, > Chris Rebert wrote: > > >>>> How do you call a function of no > arguments? > >>> > >>> It's not really a function in that case, it's > just a named constant. > >>> (Recall that functions don't/can't have > side-effects.) > >> > >> > >>>>> time.time(), random.random() > >> (1264983502.7505889, 0.29974255140479633) > >>>>> time.time(), random.random() > >> (1264983505.9283719, 0.74207867411026329) > >> > >> > >> They don't look terribly constant to me. > > > > Those aren't functions in the pure functional > programming sense; which > > is unsurprising since Python isn't a [pure] functional > language. They > > both involve side-effects. time() does I/O to the > clock chip to see what > > time it is, and random() uses and changes a global > seed value variable > > (which, in a double-whammy, takes its initial value > from time()). > > Yes, but these tasks -- get the time, get a (pseudo) random > number -- are > not unique to Python. Surely even Lisp and Haskell code > will sometimes > need to know the time. Whether they are "pure functions" > (functions in > the mathematical sense) or impure, they're still functions > in some sense. > How do you deal with such impure functions? > > > You pass it a monad (http://en.wikipedia.org/wiki/Monad_(functional_programming)). -EdK Ed Keith e_...@yahoo.com Blog: edkeith.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
