[Haskell-cafe] Unnecessarily strict implementations

Henning Thielemann lemming at henning-thielemann.de
Thu Sep 2 12:25:11 EDT 2010

On Thu, 2 Sep 2010, Stephen Sinclair wrote:

> On Thu, Sep 2, 2010 at 3:25 AM, Jan Christiansen
> <jac at informatik.uni-kiel.de> 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?

You might use or abuse (<=) for implication, however the arrow points to 
the wrong direction.

>  It seems to me a throwback to C's somewhat arbitrary assumption that False=0
> and True=1.

My feeling is similar.

The Ord instance for Bool might be justified for using Bools as keys of 
Data.Map, however you can also consider using Ord for Map as abuse.

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