Proposal: Make gcd total

Daniel Fischer at
Wed May 18 03:57:06 CEST 2011

On Tuesday 10 May 2011 08:02:50, Judah Jacobson wrote:
> On Mon, May 9, 2011 at 3:49 PM, Daniel Fischer
> < at> wrote:
> > I would like to propose the elimination of the special error case
> > 
> > gcd 0 0 = error "Prelude.gcd: gcd 0 0 is undefined"
> > 
> > to replace it with
> > 
> > gcd 0 0 = 0
> > 
> > (which would be an automatic consequence of removing the above line).
> In my email archives, I found two previous threads on the subject.
> Both ended up in favor of the proposal:
> As a result of the latter discussion, a ticket was opened on GHC's trac:
> But it was eventually closed for lack of attention.
> So if someone actually follows through with this as an official
> libraries submission (with a patch, deadline, etc.), the odds seem in
> favor of it.

I'll try to see it through, although the process seems rather daunting.
It has annoyed me for too long.

Patches for GHC are at
(plural, because the error needs to be in the haskell98 and haskell2010 
packages, since the report demands it).

Although this time there has not been much discussion yet, I refer to the 
previous discussions linked by Judah, to conclude that after some 
discussion (albeit spread over many years), the proposal seems plausible.

I hereby volunteer to become the proposal owner.


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