Parallel GHC installations

In order to ensure any package I write does in fact work with any tooling I say it does, Iʼve installed old versions of GHC to run my code through before any version release. To do so, I take advantage of the plain-text installation‐instruction files the distribution of Linux I use—Gentoo—is based around, tweaking the official files just slightly to avoid installing the typical but unversioned ghc and similar links (in favor of, e.g., ghc-8.10.4). I can then easily call these through a wrapper around cabal whenever I want to use an older compiler.

More information on actual usage to be written, but the source code should be simple enough to parse without too much trouble.