[Haskell-cafe] Test on identity?

[Simon Jakobi]

Hi Dusan,

containers uses pointer equality in some places:

https://github.com/haskell/containers/search?q=ptrEq&unscoped_q=ptrEq

I'd suggest to read up on reallyUnsafePtrEquality#, before you rely on
it though.

Hope that helps!
Simon

Am Mi., 8. Juli 2020 um 08:18 Uhr schrieb Dušan Kolář <kolar at fit.vut.cz>:
>
> Dear Café,
>
>
> I'm trying to build a DAG from a binary tree. I don't think there's a big trouble. Nevertheless, I do even some transformations. Thus, I would like to know it is still a DAG, not adding, accidentally, a node.
>
>
> Is there any way, if I have data like
>
>
> data Ex
>
>   = Val Int
>
>   | Add Ex Ex
>
>
>
> so that I can test that some value Val i === Val i ? I mean, the pointers go to the same data box? I could do that via some IORefs, AFAIK, but I don't think it is feasible. Maybe to tune the algorithm...
>
>
> Best regards,
>
>
> Dusan
>
>
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