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

29 Sep 2009


      Did you test the properFraction-based code in isolation? If code is
broken, it's important to figure out which part of it is broken. Also,
this function is not divided into constituent parts, but is a long unruly
mess. Dividing it into parts would make it much much more readable, and
you would then be able to test the parts individually.

Jimmy
...
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
Â (_, 0) -> l
Â _ -> 0 -- always goes here.
Odd, it works fine for me.
f x =
Â  Â  Â  Â case properFraction x of
Â  Â  Â  Â  Â  Â  Â  Â (_,0) -> True
Â  Â  Â  Â  Â  Â  Â  Â _ Â  Â  -> 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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Re: [Haskell-cafe] How to decide if a number is an integer?

Jimmy Hartzell