Mention hlint data file handling in readme

[jneira]

Closes #872

[Anrock]

As end-user: "Okay, hie must locate hlint file and will search at that path as a last resort. Where it will search in the first place?"

[jneira]

Uh, yeah, hlint has it own logic: afaik cwd (and parent directories) -> hlint_datadir(cabal/stack specific) env var -> $HOME (not sure about that one) -> executable current dir (the mentioned one)
Not sure about the order (but the last one) but it is hlint specific and i've dont find a link in hlint docs to point to.
Do you think that should be reflected (i had to previously read the code/test)?
My idea was: if the hlint.yaml file is not found (wherever it could be) you can put it wehre the hie executable is.

[Avi-D-coder]

I still have considerable doubts about this. It does not conform to standard UNIX packaging.
We can't place hie in /usr/bin since it would require making /usr/bin/data/hlint.yaml.
The file-embed approach is far better.

[jneira]

Jumm i've checked where my installation is searching for the file:

• It looks in the dir pointed by $HLINT_DATADIR or the default one assigned by cabal/stack (inside cabal store or .stack_root)
• If that directory nos exists it looks for it in the data subdir in the dir where the executable is.
• At least using hlint as a library, it seems it doenst search in cwd or in $HOME.

@Avi-D-coder each option has it own caveats and we decided finally to handle it like hlint itself, at least for now, without change any hie or hlint code. But i am open to talk about the file embed option, specially if it is done in hlint itself: maybe could we open an issue/pr in hlint to get feedback about?

or we can also reopen #1143 before that

[Avi-D-coder]

@jneira $HLINT_DATADIR is a runtime env right? A runtime env cannot be configured by most Linux package managers. Over riding at compile is also broken ndmitchell/hlint#699

[jneira]

Oh, didnt know, i've just tested to set the env var manually in my windows machine and it worked for me.
So i think it is worth to document how hie works right now but i will reopen the mentioned issue to discuss the file embed alternative.

[Avi-D-coder]

I sent in a file-embed PR ndmitchell/hlint#824

[jneira]

@Anrock i've tested the different locations where the file is searched and i've added them