all-hies/Design.org

Assumption: The stack build does not depend on which nixpkgs version it uses, it only needs a matching ghc version

~/.cache/all-hies/ layout:

• history-nixpkgs-unstable
• nixpkgs
• haskell-ide-engine

• per-nixpkgs

  • <nixpkgsrev-ghcVersions>: File with a list of ghc versions this nixpkgs rev has

• per-haskell-ide-engine

  • <hie-rev>

    • <ghcVersion-stack2nix>.nix: File generated by stack2nix for hie-rev and ghcVersion

./generated/ layout:

• nixpkgsForGhc

  • <ghcVersion>: File containing the nixpkgsrev to use for that ghc

• stable

  • <ghcVersion>.nix: File copied from the cache
  • revision: File with the git revision of current stable hie

• unstable

  • <ghcVersion>.nix: File copied from the cache
  • revision: File with the git revision of current unstable hie

Flags:

• Whether master should be regenerated
• Whether to build the generated versions with Nix

Process:

• Update/initialize hie repo

• Regenerate ./generated/stable by

  • Removing ./generated/stable/*
  • Getting the latest tag (~=stable)
  • Write stable tag to ./generated/stable/revision
  • Determining the stable hie sha1 hash from the tag
  • Checking out that hie revision

  • For each stack file for a ghc version

    • If $CACHE/per-hie/<rev>/<ghcVersion>.nix is present

      • copy it to ./generated/stable/<ghcVersion>.nix

    • else generate that file by

      • Find a suitable nixpkgs revision for that ghc version

        • If ./generated/nixpkgsForGhc/<ghcVersion> present, use that version

        • else

          • fetch channel history (or use cached version if <15 minutes ago)

          • for each channel nixpkgs revision (from newest to oldest)

            • Get ghc versions

              • If $CACHE/per-nixpkgs/<revision> exists use that

              • Otherwise

                • Check out that nixpkgs version (and maybe update/initialize the repo first)
                • Run nix evaluation to determine available compilers
                • Save result in $CACHE/per-nixpkgs/<revision>

            • If it has the ghc version we need

              • Save that revision in ./generated/nixpkgsForGhc/<ghcVersion>
              • revision found, exit channel history loop
            • Otherwise continue
          • If no fitting ghc version was found, log error
      • Checking out that nixpkgs revision
      • Invoke stack2nix to generate $CACHE/per-hie/<rev>/<ghcVersion>.nix
      • If nix build flag is enabled, build it
      • Copy $CACHE/per-hie/<rev>/<ghcVersion>.nix to ./generated/stable/<ghcVersion>.nix

• If master flag is enabled, regenerate ./generated/unstable by

  • (same process as above, only difference is first step)