[Haskell-cafe] On the purity of Haskell

[Steve Horne]

On 29/12/2011 19:55, Bardur Arantsson wrote:
> On 12/29/2011 08:47 PM, Steve Horne wrote:
>> On 29/12/2011 19:21, Heinrich Apfelmus wrote:
>>>
>> BTW - why use an IO action for random number generation? There's a
>> perfectly good pure generator. It's probably handy to treat it
>> monadically to sequence the generator state/seed/whatever but random
>> number generation can be completely pure.
>
> *Pseudo* random number generation can of course be pure (though 
> threading the state would be tedious and error-prone). If you want 
> truly random numbers you cannot avoid IO (the monad).
On the threading the state thing - it doesn't matter whether it's the IO 
monad or the State monad (a perfect wrapper for the seed).

For where-does-the-entropy-come-from, though, yes - I guess you're right.