I very much doubt that Num a is sufficient. That's not even enough to check whether a number is even. You can certainly perform the calculation with `Integral a`, but you'll have to apply some external reasoning to see that the result is correct. On Wed, Dec 16, 2020, 4:45 PM M Douglas McIlroy < m.douglas.mcilroy@dartmouth.edu> wrote:
Some nominally rational functions, e.g n*(n+1)/2, yield integer values for integer arguments. I seek either a way to wrap such a function so it has type Num a => a->a or a convincing argument that it can't be done.
Doug _______________________________________________ Haskell-Cafe mailing list To (un)subscribe, modify options or view archives go to: http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe Only members subscribed via the mailman list are allowed to post.