Re: [Haskell-cafe] I need help getting started

Mitchell You might also be interested in the beginners mailing list. I've been enjoying for about a month now! http://www.haskell.org/mailman/listinfo/beginners On Sat, Apr 24, 2010 at 9:57 PM, Luke Palmer wrote:

On Sat, Apr 24, 2010 at 10:34 PM, wrote:

...

Hi,

I’m just starting to learn, or trying to learn Haskell. I want to write a function to tell me if a number’s prime. This is what I’ve got:

f x n y = if n>=y

then True

else

if gcd x n == 1

then f x (n+1) y

else False

primeQ x = f x 2 y

where y = floor(sqrt(x))

Pretty good so far. The only trouble is that the type of x is inconsistent. In f it is an integer, but in primeQ it is a floating point (because you are taking its square root). Getting past this just involves understanding Haskell's type system peculiarities. Change that last line to:

where y = floor (sqrt (fromIntegral x))

And you should be fine. (Untested)

In the future, post the error that you are getting addition to the code that is causing it. That helps us find it faster.

Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe