[Haskell-cafe] Confused by ghci output

[Kevin Charter]

Hi Clark,

On Thu, May 31, 2012 at 10:35 AM, Clark Gaebel <cgaebel at uwaterloo.ca> wrote:

> *X> 3^40 `mod` 3 == modexp2 3 40 3
> False
> *X> modexp2 3 40 3
> 0
> *X> 3^40 `mod` 3
> 0
>
> I'm confused. Last I checked, 0 == 0.
>

Your HPaste shows the type of modexp2 is Int -> Int -> Int -> Int, so ghci
will infer that (3^40) is an Int. But an Int isn't big enough to hold 3^40.

Prelude> 3^40 :: Int
-6289078614652622815
Prelude> (3^40 :: Int) `mod` 3
2

Kevin
-- 
Kevin Charter
kevin.charter at acm.org
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