[m-users.] Impurity needed?

[Volker Wysk]

Am Dienstag, dem 14.02.2023 um 01:05 +1100 schrieb Zoltan Somogyi:
> If you need an equivalent of Haskell's unsafe_perform_io, and it seems you do,
> you can build it yourself like this:
> 
> promise_pure (
>   some [!IO] (
>     io.unsafe_get_io_state(!:IO),
>     ...,
>     io.unsafe_set_io_state(!.IO)
>   )
> )
> 
> unsafe_{get,set}_io are the primitives that the compiler uses
> to implement trace [io(!IO)]. We don't advertise them, since we want to
> discourage their use, but there is no point in hiding them either,
> because it is trivial to implement them using foreign_procs anyway.

This looks very interesting. I have to play with it. :-)

Volker
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: This is a digitally signed message part
URL: <http://lists.mercurylang.org/archives/users/attachments/20230213/8c8833c5/attachment.sig>