The GHC development has a constant influx of new innovations. As a decent-sized young company in the fintech industry with lots of stakeholders’ interests, at Mercury, we want to boost up developer’s productivity rapidly from such innovations while operating safely with stable compiler infrastructure.

In this talk, I would like to share our experience collaborating with GHC experts for new feature developments in the GHC upstream and how to apply it to our product development timely by keeping the integration cycle as short as possible. Along with product build configuration with nix-based GHC and libraries, I show how we manage semi-continuous integration of GHC HEAD into the product build, empowered by the community-provided assets like hackage, head.hackage and nixpkgs. Hardened nixified GHC and flexible GHC HEAD coexist and benefit each other in a few of very different build setups: integrated with Cabal-based build system and new buck2-based build system. Identifying key ingredients for testing GHC HEAD in an industrial setup continuously, we will have discussion about desirable strategies on GHC API stability layers, community infrastructure management and industry roles in fast GHC release adoption.