type of stToIO

[Marcin 'Qrczak' Kowalczyk]

Thu, 5 Oct 2000 09:25:18 -0700, Simon Peyton-Jones <simonpj at microsoft.com> pisze:

> I discussed this with John Launchbury who pointed out a much
> better type for stToIO
> 
> 	stToIO :: (forall s. ST s a) -> IO a
> 
> That avoids exposing RealWorld while preserving soundness.  Better, eh?

Doesn't it prevent returning a value of type STRef RealWorld something
from the computation, which is a perfect IORef something substitute
when we have stToIO?

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