[m-rev.] for review: disallow impure parallel conjuncts

[Julien Fischer]

On Tue, 15 Aug 2006, Peter Wang wrote:

> Estimated hours taken: 1.5
> Branches: main
>
> Disallow impure parallel conjuncts as they can introduce concurrency issues.
> e.g. in the following X could be bound to `foo' or `bar' in different runs.
>
>    impure set_mutvar(foo),
>    (
> 	semipure get_mutvar(X)
>    &
> 	impure set_mutvar(bar)
>    )

Is that a reason for disallowing them though?  Presumably at some point
I'm going to have to promise that is pure - if there are concurrency
issues then either the promise is a lie.  I don't necessarily see
why the following should be not allowed:

      (
         impure foo
      &
         impure something_unrelated_to_foo
      )

If the code is impure then it is up to the programmer to ensure its
correctness.

Julien.
--------------------------------------------------------------------------
mercury-reviews mailing list
Post messages to:       mercury-reviews at csse.unimelb.edu.au
Administrative Queries: owner-mercury-reviews at csse.unimelb.edu.au
Subscriptions:          mercury-reviews-request at csse.unimelb.edu.au
--------------------------------------------------------------------------