Are you looking for numbers that are squares, or any power (probably any power at least two)? If it's the latter you need something more interesting that sqrt. An alternative to squaring the number agagin is to use properFraction. Brandon On Fri, 7 Nov 2003, Hamilton Richards wrote:

Also note that

if x then True else False

is just a verbose way of writing

x

At 2:51 PM -0800 11/7/03, Hal Daume III wrote:

...

try "floor (sqrt (fromIntegral n))"

On Fri, 7 Nov 2003 ddekker6@chello.nl wrote:

...

hello all,

im new to haskell and have to do some excersises. Well i ran into this problem. I have to determin if a list of int's contains a int that is a power. So i have been trying using "any" with a helper function which return a Bool if the int is a power and applying that to the list. I think that this aproach should work. Anyway the problem im having is in the helper function. I have been trying this: isPower n = let powerF = floor(sqrt(n)) in if (powerF*PowerF == n) then True else False

[...] -- ------------------------------------------------------------------ Hamilton Richards, PhD Department of Computer Sciences Senior Lecturer The University of Texas at Austin 512-471-9525 1 University Station C0500 Taylor Hall 5.138 Austin, Texas 78712-1188 ham@cs.utexas.edu hrichrds@swbell.net ------------------------------------------------------------------ _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe

But note that x `seq` x is equivalent to x, even operationally. To see why denotationally, note that if x evaluates to _|_, so does x `seq` x. And if x evaluates to a value v, so does x `seq` x. To see why operationally, consider the two lists: let x = 1+1 in [x `seq` x] let x = 1+1 in [x] Using conventional lazy evaluation in both cases, the term "1+1" is not evaluated until the head of the list is taken. In other words, x `seq` x in no way hurries the evaluation of x. -Paul Wolfgang Jeltsch wrote:

Am Samstag, 8. November 2003, 00:22 schrieb Hamilton Richards:

...

Also note that if x then True else False is just a verbose way of writing x

Actually, it's just a verbose way of writing x `seq` x, but this detail is, of course, not interesting for beginners.

Wolfgang

On Saturday 08 November 2003 04:31 am, Wolfgang Jeltsch wrote:

Am Samstag, 8. November 2003, 00:22 schrieb Hamilton Richards:

...

Also note that

if x then True else False

is just a verbose way of writing

x

Actually, it's just a verbose way of writing x `seq` x, but this detail is, of course, not interesting for beginners.

?? Sorry, but x `seq` x is just a verbose way of saying x. Matt