The instructions are quite clear. Alas, when I try to reproduce the steps using my home-build compiler (for which I mean set the `with-compiler` in `cabal.project` to the stage2 compiler obtained by Hadrian), I get:

> cabal new-install --lib aeson
Distribution/Client/CmdInstall.hs:(361,18)-(363,72): Non-exhaustive patterns in lambda

Do you have any idea of what I might be doing wrong?

Thanks in advance,
Alejandro

El mar., 10 sept. 2019 a las 12:32, Ben Gamari (<ben@smart-cactus.org>) escribió:
Alejandro Serrano Mena <trupill@gmail.com> writes:

> Dear GHC devs,
> As part of our work in "quick look impredicativity", we would like to test
> whether any package breaks. I've read about "head.hackage" as a way to test
> this fact, but I could not find any information.
>
> Could somebody point me in the right direction? If it does not exist yet,
> I'll try to summarize whatever I learn in the wiki for future reference.
>
Hi Alejandro,

Indeed I have a pair of yet-to-be-published blog posts intended to
discuss exactly this. See [1] and [2]. Do let me know if you have any
questions.

Cheers,

- Ben


[1] https://gitlab.haskell.org/ghc/homepage/merge_requests/16/diffs
[2] https://gitlab.haskell.org/ghc/homepage/merge_requests/29/diffs