GHCi Support

[friedbrice]

Maybe this is a naive question, but these typechecker plugins work with GHCi as well, right?

Using Ghcid to invoke GHCi with these plugins enabled will provide an IDE-like experience. All that's needed are editor plugins that read the files created by these plugins.

VS Code has something similar already: https://marketplace.visualstudio.com/items?itemName=ndmitchell.haskell-ghcid (And it always works, with any haskell project, and it's a joy to use.)

I think a crucial thing that makes this approach tenable is that it only re-compiles on file saves, so only on discrete, human-initiated times. whereas something like HLS is continually recompiling (IIUC). This saves on system resources so that the computer only does this work when it's relevant to a human operator. (To be honest, I prefer to defer feedback to file saves anyway. I hate it when I'm in the middle of typing and all of a sudden the squiggly red underlines go crazy.)

[friedbrice]

(Having said all that, I can't help but feel bad that we're effectively side-stepping HLS with this plugin approach, right? That just seems kinda wrong.)

[wavewave]

I would say that the HLS approach and this plugin approach are actually complementary. What HLS does is to provide a global indexing environment over the code base by continuously checking and updating information commonly used. The inspection plugin is intended to provide targeted analysis for a certain feature (in a batch compilation execution). Currently, the workflow I consider as a primary use case is that developers can just turn a specific plugin on for identifying a problem, benchmarking or troubleshooting and turn off the plugin after that. In that vein, one of the closest examples to this plugin toolbox is inspection-testing.

[wavewave]

How to effectively use ghci with ghc plugin is an interesting use case to explore. Thanks for the note! :-)

[wavewave]

Currently started to work on this. We found big memory retention in GHCi session after reloading a big module subtree, and want to inspect it on live.