Write hie info

[balacij]

Contributes to #3700 by writing HIE information necessary for both stan and weeder

[balacij]

Force-pushed to remove a commit I didn't intend to write to this branch...

[JacquesCarette]

Look fine to me, but I want to understand a bit better first. What are .hie directories?

[balacij]

Yep, .hie files are snapshots of key information found about a codebase by GHC (while it was compiling said codebase). From what I've understood, its ultimate goal is to enable external tools to 'search/analyze/manipulate the AST' as if it were built into the compiler itself. One of the key benefits to that approach is that they can rely on GHC's Haskell parser. Notably, stan and weeder use .hie information to examine Haskell programs.

The hiedb package allows us to write Haskell code that handles the .hie information (hence enumerating what information we can readily see from the GHC output), and it also has a nifty 'Query' module that we might be able to use as well! For example, we have those two scripts in the scripts/ folder -- I forget what they do completely, but I know they scan the source code -- that could probably be simplified by relying on the .hie information instead of a string search. Maybe we make that a work task actually? I'm not sure how robust those scripts are.

[balacij]

@JacquesCarette I see on #3739, you mentioned that you wanted more information about this -- did the above comment clarify everything?

[JacquesCarette]

Upon re-reading: yes.