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

Sittampalam, Ganesh ganesh.sittampalam at credit-suisse.com
Wed Sep 3 03:05:58 EDT 2008

Ashley Yakeley wrote: 

>Ganesh Sittampalam wrote:
>> In any case, what I'm trying to establish below is that it should be
>> safety property of <- that the entire module (or perhaps mutually 
>> recursive groups of them?) can be duplicated safely - with a new
>> or as if with a new name - and references to it randomly rewritten to

>> the duplicate, as long as the result still type checks.

> That's not acceptable. This would cause Unique to break, 
> as its MVar would be created twice. It would also mean 
> that individual Unique and IOWitness values created by
> <- would have different values depending on which bit 
> of code was referencing them. It would render the extension
> useless as far as I can see.

The result wouldn't typecheck if two Unique values that now pointed to
the two different modules were compared.


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