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"],
            "initializationOptions": {
                "languageServerHaskell" : {
                    "hlintOn": true,
                    "maxNumberOfProblems": 10,
                    "completionSnippetsOn": true
                }
            }, "settings" : {
                    "haskell": {
                        "checkParents": "CheckOnSave",
                        "checkProject":true,
                        "formattingProvider": "fourmolu",
                        "formatOnSave": true,
                        "tabSize": 4,
                        "detectIndetation": false,
                        "insertSpaces": true
                    }
            }
        },
        "clangd": {
            "command": "clangd",
            "rootPatterns": ["compile_flags.txt", "compile_commands.json"],
            "filetypes": ["c", "cc", "cpp", "c++", "objc", "objcpp"]
        }
    }
}