[Haskell-cafe] Very freaky

[Andrew Coppin]

Stefan O'Rear wrote:
> On Tue, Jul 10, 2007 at 08:59:16PM +0100, Andrew Coppin wrote:
>   
>> I find myself wondering... A polymorphic type signature such as (a -> b) -> 
>> a -> b says "given that a implies b and a is true, b is true". But what 
>> does, say, "Maybe x -> x" say?
>>     
>
> Given that x may or may not be true, x is definitely true.
>
> Which, of course, is absurd.
>   

...which, presumably, is because a (pure) function with that type might 
be able to fail?