Thanks, Georgi and Sebastian.
The instructions at https://github.com/alpmestan/ghc.nix and https://ghc.dev/ seem a bit outdated, then. I’m not sure who maintains those. In the README.md https://readme.md/ for ghc.nix, it says to run: nix-shell https://github.com/alpmestan/ghc.nix/archive/master.tar.gz --attr devShells.<your-system>.default That failed didn’t work for me and I was told I needed to use nix-develop, which worked. Then later, it says to run: $ ./boot && ./configure $CONFIGURE_ARGS # In zsh, use ${=CONFIGURE_ARGS} …which as you pointed out should be updated to configure_ghc. Anyway, that got me further, but I still get several fatal errors of this sort: compiler/GHC/Tc/Zonk/Type.hs:1277:13: error: • Illegal equational constraint Anno (StmtLR GhcTc GhcTc (LocatedA (body GhcTc))) ~ SrcSpanAnnA (Use GADTs or TypeFamilies to permit this) • In the type signature: zonkStmt :: Anno (StmtLR GhcTc GhcTc (LocatedA (body GhcTc))) ~ SrcSpanAnnA => (LocatedA (body GhcTc) -> ZonkTcM (LocatedA (body GhcTc))) -> Stmt GhcTc (LocatedA (body GhcTc)) -> ZonkBndrTcM (Stmt GhcTc (LocatedA (body GhcTc))) | 1277 | zonkStmt :: Anno (StmtLR GhcTc GhcTc (LocatedA (body GhcTc))) ~ SrcSpanAnnA | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^... Command failed Build failed. Georgi, I might just ping you on Slack about it. (We’re coworkers.) Thanks, Lyle