Re: An answer and a question to GHC implementors [was Re: How to make Claessen's Refs Ord-able?]

On Tue, Apr 09, 2002, Simon Marlow wrote:

<muse> I did wonder once whether IO monad bindings should be allowed at the top-level of a module, so you could say

module M where ref <- newIORef 42

and the top-level IO would be executed as part of the module initialization code. This solves the problems with unsafePerformIO in a cleanish way, but would add some extra complexity to implementations. And I'm not sure what happens if one top-level IO action refers to other top-level IO bindings (modules can be recursive, so you could get loops too). </muse>

First-class modules could (I believe) solve this problem quite neatly. David