[Haskell-cafe] Monte Carlo Pi calculation (newbie learnings)

[David Roundy]

On Mon, Nov 05, 2007 at 01:42:50PM -0700, Luke Palmer wrote:
> On Nov 5, 2007 1:30 PM, Jonathan Cast <jonathanccast at fastmail.fm> wrote:
> > Get an infinite list of pairs
> >
> > >   let pairs = [ (x, y) | x <- randoms (-1, 1) g0,
> > >                          y <- randoms (-1, 1) g1 ]
> 
> This will return a list like [(a,b),(a,c),(a,d),(a,e),...].  This
> needs to be a parallel comprehension:
> 
> let pairs = [ (x,y) | x <- randoms (-1,1) g0 | y <- randoms (-1,1) g1 ]

Or even better, just don't use list comprehensions, they're confusing:

let pairs = zip (randoms (-1,1) g0) (randoms (-1,1) g1)

Now you don't have to think backwards to figure out what the comprehension
is doing.
-- 
David Roundy
Department of Physics
Oregon State University