Agentultra - Using Haskell in Production

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I get asked on my stream and at talks I give, “What is it like to work in Haskell in production, full-time?”From November of 2020 until August 2025, I was employed at Mercury where I wrote code in Haskell.During that time I also started up a live video stream where I’ve built several libraries, games, and applications in Haskell for an audience.This post is a summary of my experiences from those 4.5 years where I worked on a team of 20-some-odd developers writing Haskell that grew into a company with over a hundred developers. A lot of my experiences are flavoured by that unique situation. Be aware that this post is more of an experience report than a broad survey of Haskell in industry.Let’s start with some of the trade-offs and difficulties that adopting Haskell has.Trade OffsHaskell has been around a long time and is a stable language and ecosystem to develop software on. However it is not a mainstream language. That is both a blessing and a curse.EcosystemThere is a new softwa…