Re: [Haskell-cafe] Unnecessarily strict implementations

On 02/09/10 17:10, Stephen Sinclair wrote:

On Thu, Sep 2, 2010 at 3:25 AM, Jan Christiansen wrote:

...

I prefer

False<= _|_ = True

Sorry to go a bit off topic, but I find it funny that I never really noticed you could perform less-than or greater-than comparisons on Bool values. What's the semantic reasoning behind allowing relative comparisons on booleans? In what context would you use it? It seems to me a throwback to C's somewhat arbitrary assumption that False=0 and True=1.

Comparison on Bool itself is probably not particularly useful. But it is often useful if the Bool is part of a larger data structure. For example, I might want to have Set (String, Bool); without the Ord instance on Bool I couldn't do this. Similarly, you couldn't derive Ord on your data types that have Bool in them without the Ord Bool instance. Thanks, Neil.