[Haskell-cafe] Ord type on lists

[Claus Reinke]

> Hi everyone, I defined my own list datatype and then tried to declare
> it as an instance of type class Ord. However when I test it with
> 
> Nil > Cons 1(Nil)
> I get an "ERROR - Control stack overflow"
> 
> I am under the impression that the ord class defines default
> implementations of (<=), (>),(>=) so that I only have to supply the
> implementation of (<) shown below. Can some one tell me why this does
> not work the way I expect it to?

Now, whereever did that interpretation come from?-) 

The library docs are pretty clear about what constitutes a minimal definition:

http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#t%3AOrd

Have a closer look at Ord and its default definitions to see what happens in 
your case:

http://www.haskell.org/onlinereport/basic.html#sect6.3.2

hth,
claus