They are in fact not widely used. Ormolu and Fourmolu That's only one formatter; the latter is a fork of the former... which is the in-house formatting tool o

They are in fact not widely used. Ormolu and Fourmolu That's only one formatter; the latter is a fork of the former... which is the in-house formatting tool of one particular consulting firm. It has only existed since 2018, and is said to be mainly a response to golang/rust people trying to impose their culture on the Haskell world. Pointing at ormolu is kinda like saying that formatters are popular in the Java world because google-java-format exists. The fact that that project exists says more about the company that created it than the community around the language it operates on.