[Haskell-beginners] Help with types

Daniel Carrera daniel.carrera at theingots.org
Thu Apr 23 10:25:25 EDT 2009

Thomas Davie wrote:
>> It looks like (/) is happy with Num but doesn't like Int. This 
>> surprises me. I would have thought that Fractional is a kind of Num 
>> and Int is a kind of Fractional
> Int isn't a Fractional because it can't represent fractional numbers.

Sure, but any integer is trivially also a fraction, so I would think 
that it would be an acceptable input for (/). On the other hand, if it 
is at all possible for a Num to contain something that cannot be 
converted to a fraction, then a Num should not be a valid input for (/).

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