add hackage/shell.nix (or flake) support

[teto]

Hi,

I want to use this program to help me debug some .hie files but I have some issues indexing my hie files.
Both the .hie file and hiedb should have been compiled with ghc 8.8.3 yet I get:
IncompatibleSchemaVersion {expectedVersion = 19998083, gotVersion = 19998084}
if I use ghc884 for hiedb, I get.
readHieFile: hie file versions don't match for file: /home/teto/user_cache/f3097620197e6c203645e1230d1ae88c/execroot/toplevel_workspace/bazel-out/Porcupine.hie Expected 8084 but got 8083. Maybe my .hie files were compiled with different compilers but that would be suprising :s

It would make it easier to integrate in my project if it was on hackage or available as a nix package.
Cheers

[wz1000]

For the first error, you need to delete your default hiedb (should be in ~/.local/share). I can fix such errors by adding the schema version to the filename of the local db. Thanks for the bug report!

I will upload this to hackage soon.

[teto]

ha that was a hard one. Wouldn't naming the db ~/.local/share/default_883.hiedb avoid that ?

Cool for hackage !

[wz1000]

yeah, that's what I'll do. I just introduced the schema recently, and didn't notice this bug since I've been using it with ghcide, which manages its own database location and names it properly according to the ghc version.

[wz1000]

Fixed one part of this issue in bb789d3

[wz1000]

Closing in favor of #24