[ahakki]

stack for haskell

nix package manager

[exogen]

Note that npm also supports having multiple versions of the same package installed just fine.

The problem:

I use X to create an object with library A v1.0.

I use Y to create an object with library A v2.0.

These objects are not necessarily compatible, so X and Y have problems communicating.

I would be very surprised if you told me nix or stack inherently make objects from multiple versions of the same library magically compatible with each other.

Feel free to close issues like this one if I'm wrong: https://github.com/NixOS/nixpkgs/issues/30551

[Risord]

Hmm I think this should go something like this:

How would objects created from X and Y can reach each other and communicate when X is not dependent from Y or otherwise? You need global mutable state or your own code witch depends from both X and Y is somehow connecting them.

So one top thing FP movement argues against is global mutable state so of course you don't have that ...Unless you are wrapping some non-FP thing like QT...

And if it's your own code it shouldn't be different that Y creates B:s instead of A v2 since your code is aware from two different versions anyway.

Do you see any weak points?