Re: [Haskell-cafe] Re: gcd

Am Sonntag 03 Mai 2009 00:17:22 schrieb Achim Schneider:

Steve wrote:

...

"It is useful to define gcd(0, 0) = 0 and lcm(0, 0) = 0 because then the natural numbers become a complete distributive lattice with gcd as meet and lcm as join operation. This extension of the definition is also compatible with the generalization for commutative rings given below."

Ouch. Speak of mathematicians annoying programmers by claiming that 0 isn't divisible by any of [1..],

Beg pardon? 0 is divisible by all of them. And while we're talking about rings, 0 is also divisible by 0.

and further implying that 0 is bigger than all of those,

'Tis, in the divisibility preorder :)

not to mention justifying all that with long words.

Sorry for the long words, but having gcd 0 0 == lcm 0 0 == 0 is the sensible thing and having it differently in Haskell is a bad mistake (IMO).

Damn them buggers.