[Haskell-cafe] Re: [Haskell] Top Level <-

[Ganesh Sittampalam]

On Sun, 31 Aug 2008, Brandon S. Allbery KF8NH wrote:

> On 2008 Aug 31, at 10:29, Ganesh Sittampalam wrote:
>> On Sun, 31 Aug 2008, Brandon S. Allbery KF8NH wrote:
>>> On 2008 Aug 31, at 10:20, Ganesh Sittampalam wrote:
>>>> I'm not sure of precisely what you mean here, but stdin, stdout and 
>>>> stderr are things provided by the OS to a process. That's what defines 
>>>> them as having process scope, not something the Haskell language or RTS 
>>>> does.
>>> 
>>> But their representations in Haskell must have the same scope and are 
>>> therefore de facto global variables.
>> 
>> Yep, but this is not Haskell providing a way to make global variables, it 
>> is just providing an interface to ones that already exist. The point is 
>> that the RTS can't provide (process-scope)
>
> But that is done the same way as providing general global variables, so you 
> can't get away from it.

I don't follow what you mean. stdin, stdout and stderr are just file 
descriptors 0, 1 and 2, aren't they? You can create them as many times as 
you want with using that information without causing any confusion or 
conflict. Whereas the <- proposal has a "once-only" requirement.

Ganesh