This is a totally nutty scenario. Microservices are not "do whatever you want!" - they give you the freedom to choose your stack. It is obviously still a business decision to choose Haskell and you've got other problems if developers are building things in random languages that they feel like using without a larger discussion.
The issue here isn't Haskell it's ownership and process.
The issue here isn't Haskell it's ownership and process.