Minimal effort build improvements and a GHC 8.2.2 upgrade

How attempting to speed up my CI builds led to upgrading to GHC 8.2.2 (and eventually speeding up my CI builds)

vados

19 minute read

tl;dr - On a Haskell project I’m working on I started with >~20 minute cold-cache builds in the worst case in my Gitlab-powered CI environment then found some small ways to improve. Very recently I decided I wasn’t satisfied with ~10 / 15 minute builds and did the laziest, least-effort steps I could find to get to <10 minute cold-cache builds (~5min best case). Check out the [TLDR][tldr] section to see the Dockerfiles and steps I took summarized.