Proposal: Make gcd total

[Ross Paterson]

On 28 May 2011 11:59, Daniel Fischer wrote:
> I would like to propose the elimination of the special error case
>
> gcd 0 0 = error "Prelude.gcd: gcd 0 0 is undefined"

Just deleting that line sounds good.  For documentation, I'd suggest:

  gcd x y is the non-negative factor of both x and y of which every
  common factor of x and y is also a factor; for example gcd 4 6 = 2,
  gcd (-4) 6 = 2, gcd (-4) (-6) = 2, gcd 0 4 = 4, gcd 0 0 = 0.
  (That is, the common divisor that is "greatest" in the divisibility
  ordering.)