Re: [Haskell-cafe] How to decide if a number is an integer?

29 Sep 2009


      The original code is
givenSum num = map (\a ->
                      let l = (sqrt $ fromIntegral (a * a + 2 + 2 *
num)) - (fromIntegral a) in
                      case properFraction l of
                        (_, 0) ->
                          True
                        _ ->
                          False
                   ) $ take num [1..]
:t l is (Floating a) => a
Well, in ghci
*Main> givenSum 10
[False,False,False,False,False,False,False,False,False,False]

On Tue, Sep 29, 2009 at 2:45 PM, Thomas DuBuisson
 wrote:
...
On Mon, Sep 28, 2009 at 11:35 PM, Magicloud Magiclouds
 wrote:
...
It never matches to (_, 0.0)....
I mean
case properFraction l of
 (_, 0) -> l
 _ -> 0 -- always goes here.
Odd, it works fine for me.
f x =
       case properFraction x of
               (_,0) -> True
               _     -> False
*Main> f 5
True
*Main> f 5.5
False
*Main> f 4.0
True
*Main> f 4.00000001
False
Thomas
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