On 18/09/2023 20:28, Richard Eisenberg wrote:
Bottom line for me: I think we should implement and then experiment. Given the potentially delicate nature of this, I might even advocate for implementing this in a release branch, so that as much of Hackage as possible actually has a hope of compiling. Then test to see where the breakage occurs. If were happy with the result, rebase the implementation on master. But I don't want us to get into a state where we accept, implement, observe moderate breakage, and then blast ahead because the committee approved the idea.
The breakage concern is worth thinking about, I agree, but fortunately in this instance we don't need to wait for an implementation to run an experiment. The change can be relatively effectively simulated by compiling with -Werror=missing-methods -Werror=missing-fields, and indeed Oleg has done so already for clc-stackage as he reports here: https://github.com/ghc-proposals/ghc-proposals/issues/544#issue-1410125536 https://github.com/ghc-proposals/ghc-proposals/issues/544#issuecomment-12799... Out of nearly 3000 packages, he found 22 were broken by -Werror=missing-methods and 9 by -Werror=missing-fields. Adam -- Adam Gundry, Haskell Consultant Well-Typed LLP, https://www.well-typed.com/ Registered in England & Wales, OC335890 27 Old Gloucester Street, London WC1N 3AX, England