basic ways to work with default.nix & cabal (overriding conventions etc) + local haddocks

[gspia]

Hi

I have building difficulties with a project and it seems that turning off the haddock generation is needed. The current docs don't show, how to do this. Maybe add something about it to local haddoc. Even thought this is about nix-confs

• this can be hard those who are new for both nixos and frp
• the nix-things on frp-platform build on top of nix-libs: it is not obvious, how to do things to get them working on frp-platform/ob
• it might not be that obvious for some things, should the mod made into the cabal- or default.nix-files

These "things" include

• turning on and off the documentation generation
• passing parameters to the compilation and linking, and for ghc and ghcjs
• if the system tries to compile external lib, and it is, say too new (version clash), then what is the recommended way to solve this. (Sometimes, I just get the source and refer to the local version, which probably is a bad way to do things, and sometimes I have referred to older version. The problem with that is that I cannot remember, how to do the referral to the older version and somehow I cannot find easily, where I have applied it. Both would be the default.nix-modifications.)

Further, it's probably not easy to decide, what is the right place for the above things. (Somewhere in the docs as that is the place people tend to look and not in the related project-readme-files??)