I assume the problem is that the function doesn't compile. This should work:
toIntegralList :: (Read a, Show a) => a -> [a] toIntegralList x = map (\c -> read [c]) (show x) This adds the required Read and Show instances, which are necessary because of the read and show functions, respectively. Also note that I have omitted your extra type annotation, which also causes an compile error.
The problem with this functions is that you can use it on a lot of stuff that isn't a number, and you'll get a runtime read error, to remedy this, just reinsert the Integral type class requirement:
toIntegralList :: (Integral a, Read a, Show a) => a -> [a] toIntegralList x = map (\c -> read [c]) (show x)
Hope this helps, Paul William Gilbert wrote:
I am trying to write a function that will covert either an integer or an int into a list containing its digits.
ex. toIntegralList 123 -> [1,2,3]
I have written the following definition that tries to use read to generically cast a string value to an Integral type that is the same as the Integral passed in:
toIntegralList :: (Integral a) => a -> [a] toIntegralList x = map (\c -> read [c] :: a) (show x)
I understand it would be very simple to just create two functions, one that converts an Int and one that converts an Integer, however I was wondering if there were any way to accomplish what I am trying to do here.
Thanks In Advance, Bryan _______________________________________________ Beginners mailing list Beginners@haskell.org http://www.haskell.org/mailman/listinfo/beginners