[Haskell-cafe] How to decide if a number is an integer?
jim at shareyourgifts.net
Tue Sep 29 03:07:05 EDT 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.
> 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) ->
> _ ->
> ) $ take num [1..]
> :t l is (Floating a) => a
> Well, in ghci
> *Main> givenSum 10
> On Tue, Sep 29, 2009 at 2:45 PM, Thomas DuBuisson
> <thomas.dubuisson at gmail.com> wrote:
>> On Mon, Sep 28, 2009 at 11:35 PM, Magicloud Magiclouds
>> <magicloud.magiclouds at gmail.com> 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
>> *Main> f 5.5
>> *Main> f 4.0
>> *Main> f 4.00000001
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