[Haskell-cafe] Idea for hackage feature

[Ivan Lazar Miljenovic]

On 16 September 2010 16:04, Mitar <mmitar at gmail.com> wrote:
> Hi!
>
> I just got an idea for hackage feature. All functions/modules listed
> there could have some mark if they or any function/module they use
> uses an unsafe* function. Of course this will make probably almost
> everything marked as unsafe, but this is the idea - to raise awareness
> about that so that you can prefer some function/implementation over
> another.
>
> Of course marking/tagging everything as unsafe is not really useful.
> Because of this I propose that then community votes/vouches on
> correctness/stability of implementations and this would then influence
> the how unsafe given function really is (or is according to community,
> if we are more precise). Of course it would be even better that every
> function using unsafe would have also a formal proof but as we cannot
> believe that we will prove everything in a feasible feature we could
> maybe opt for such "crowd intelligence" approach. We cannot have a
> Turing machine, but maybe we can have crowd. ;-)
>
> (Of course low number of found bugs and good unit test code coverage
> can then positively influence crowd, so authors would be motivated to
> assure that.)
>
> Comments? Opinions?
>
> Because I really hate that I try to keep my code pure and separate IO
> from everything else and then somewhere deep in there some unsafe*
> lurks. (Ah, yes, a side effect of this tagging/marks would be also
> that you would be able to see where all those unsafe* calls are for a
> given function, so you would be able to fast jump (with link) to a
> given line in code and evaluate circumstances in which that unsafe*
> call is made. And then vote/vouch once you discover that it is
> probably pretty safe.)

The problem with this is: unsafe* functions would be better called
"yesIGuaranteeThatUsingThisFunctionDoesResultInAReferentiallyTransparentEntityAndItsOKForMeToUseIt*".
 They are "unsafe" in that you shouldn't use them blindly.

Seeing as how lazy IO relies on various unsafe* functions, as do
bytestrings, this means that any program that uses them is
subsequently "tainted".

A much better idea would be to have some kind of compilation warning
unless you can prove that you're using the unsafe* function in a safe
fashion, but such a proof is unlikely to be easily proven in a
rigorous fashion nor mechanically checkable (and would delay
compilation times).

-- 
Ivan Lazar Miljenovic
Ivan.Miljenovic at gmail.com
IvanMiljenovic.wordpress.com