Updated README installation instructions

[ianchanning]

This are some modifications based on the confusion/problems I hit with #997.

• Fedora library installation instructions
• Added a step to check GHC version before installing
• Handle each GHC version independently
• Put the step to install all GHC versions at the end and with a warning for the installation size and time taken

[alanz]

The preferred installation mechanism is actually via the makefile, as it makes sure the repo is synced, installs the required cabal libraries if missing, and makes copies of the executables with suffixes to be able to tell them apart.

So stack install will install a single version of hie, and the hie-wrapper exe will then be useless.

So, the split out/reorganise makes sense, but the "active" command should be something like

make hie-8.6.2

Also, running just make prints a list of the available targets, including the compiler versions.

[ianchanning]

Ah ok, sorry. I just blindly followed the commands in the README!

I'll have another try and re-submit.

I think the GHC version check step is still useful?

[alanz]

I think clearly documenting how to install for just the versions of GHC you care about is a good thing. And that is basically what the version check does.

[ianchanning]

I've replaced all stack install steps with make plus with the addition of the hoogle docs for an individual version. I followed these steps as well to install both the v8.6.2 and v8.4.4 versions and tested them with a yesod project using Vim and Neovim.

[alanz]

looks good, thanks for all the effort in doing this with verification.

[ianchanning]

Great, glad to help!