From the Download page[1]: > Copilot is implemented as a Embedded Domain Specific Language in Haskell. Currently Copilot 3.1 requires a version of the Glasgow

From the Download page[1]: > Copilot is implemented as a Embedded Domain Specific Language in Haskell. Currently Copilot 3.1 requires a version of the Glasgow Haskell Compiler (GHC) of at least 8.0 to be installed. So yeah, looks like Haskell because it is Haskell! :) [1]: https://copilot-language.github.io/download.html https://copilot-language.github.io/download.html