You can always write it like this: listPairs = [ (x,y) | x <- [6 .. 499] , y <- [0 .. 1000] , isProduct x , isSqrt y , mod y x == 0 ]
So you have the bounds for x and y, and then the conditions. You then need to define isProduct and isSqrt with types isProduct :: Int -> Bool isSqrt :: Int -> Bool Hopefully, these problems will look easier separately. Well, it's just an idea. Good luck, Daniel Díaz. On Tue, May 14, 2013 at 4:57 PM, John <knowledge1...@gmail.com> wrote: > Hi, > > I have to write a function which returns a list of all pairs (x,y) where x, > y ∈ N AND: > – x is the product of two natural numbers (x = a · b, where a, b ∈ N) AND > – x is really bigger than 5 but really smaller than 500, AND > – y is a squer number (y = c² where c ∈ N) NOT greater than 1000, AND > – x is a divisor of y. > > My attempt is as follows: > > listPairs :: [(Int, Int)] > listPairs = [(x,y) | x<-[0..], y<-[0..], x<-[0..]*[0..], x > 5, x < 500, > (y*y) < 1001, mod y x == 0] > > However it doesn't work unfortunatly > > Could anyone tell me where my mistake is? > > Thanks. > > > > -- > View this message in context: > http://haskell.1045720.n5.nabble.com/list-comprehension-doesn-t-work-tp5730158.html > Sent from the Haskell - Haskell-Cafe mailing list archive at Nabble.com. > > _______________________________________________ > Haskell-Cafe mailing list > Haskell-Cafe@haskell.org > http://www.haskell.org/mailman/listinfo/haskell-cafe > -- E-mail sent by Daniel Díaz Casanueva let f x = x in x
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