neovim-config/coc-settings.json

{
    "languageserver": {
        "haskell": {
            "command": "haskell-language-server-wrapper",
            "args": ["--lsp"],
            "rootPatterns": ["*.cabal", "stack.yaml", "cabal.project", "package.yaml", "hie.yaml"],
            "filetypes": ["haskell", "lhaskell"]
        }
    }
}