Explain that cabal repl --with-ghc=doctest-parallel can't exist

[ysangkok]

In the "Future of this project" section, it is said that

It would be lovely if we could get rid of the needs for write-ghc-environment-files: always

Doctest-0.20 allows for a new repl invocation mechanism, mentioned in their changelog. For Servant, it seems to enable getting rid of the mentioned flag.

It seems that this trick can't work for doctest-parallel, since there is no executable to reference. Is that correct? Would you accept a PR explaining this?

[martijnbastiaan]

Yes, that's correct. Using cabal repl would get us back to running against the interpreted code, which is something doctest-parallel is trying to avoid.

Would you accept a PR explaining this?

Absolutely!

As a side-note; cabal-docspec parses files in dist-newstyle to find libraries and package dbs. This would be a way to get rid of environment files. I opted not to when I started working on doctest-parallel, because I felt it was too much effort for something that other build tools (stack/nix) handle without any custom logic.