LSP Integration

Fresh has native support for the Language Server Protocol (LSP), providing features like:

• Real-time diagnostics: See errors and warnings in your code as you type.
• Code completion: Get intelligent code completion suggestions.
• Go-to-definition: Quickly jump to the definition of a symbol.

Built-in LSP Support

Fresh includes built-in LSP configurations for many languages. Install the server and Fresh will use it automatically:

Language	LSP Server	Install Command
Rust	rust-analyzer	rustup component add rust-analyzer
Go	gopls	go install golang.org/x/tools/gopls@latest
TypeScript/JavaScript	typescript-language-server	npm install -g typescript-language-server typescript
Python	pylsp	pip install python-lsp-server
Java	jdtls	brew install jdtls
Zig	zls	brew install zls
LaTeX	texlab	brew install texlab
Markdown	marksman	brew install marksman
C/C++	clangd	brew install llvm

Python LSP Configuration

The default Python server is pylsp. Alternatives:

Using pyright (recommended for type checking):

{
  "lsp": {
    "python": {
      "command": "pyright-langserver",
      "args": ["--stdio"],
      "enabled": true
    }
  }
}

Install pyright with: npm install -g pyright or pip install pyright

Using basedpyright (enhanced pyright fork):

{
  "lsp": {
    "python": {
      "command": "basedpyright-langserver",
      "args": ["--stdio"],
      "enabled": true
    }
  }
}

Install basedpyright with: pip install basedpyright or uv pip install basedpyright

Using pylsp with plugins:

pylsp supports various plugins for enhanced functionality:

{
  "lsp": {
    "python": {
      "command": "pylsp",
      "args": [],
      "enabled": true,
      "initialization_options": {
        "pylsp": {
          "plugins": {
            "pycodestyle": { "enabled": true },
            "pylint": { "enabled": true }
          }
        }
      }
    }
  }
}

Configuring LSP for a New Language

To add LSP support for a language, you need to configure two sections in your ~/.config/fresh/config.json:

1. languages: Define the file extensions for the language
2. lsp: Configure the language server command

For example, to add C# support:

{
  "languages": {
    "csharp": {
      "extensions": ["cs"],
      "grammar": "c_sharp",
      "comment_prefix": "//",
      "auto_indent": true
    }
  },
  "lsp": {
    "csharp": {
      "command": "/path/to/csharp-language-server",
      "args": [],
      "enabled": true
    }
  }
}

The language name (e.g., "csharp") must match in both sections. Fresh includes built-in language definitions for Rust, JavaScript, TypeScript, and Python.

Configuring Language Detection via Settings UI

You can also configure language detection using the Settings UI instead of editing config.json directly:

1. Open Settings: Use Edit → Settings... or the command palette (Ctrl+P) and search for "Settings"
2. Navigate to Languages: Go to the Languages section
3. Add or Edit a Language: Click on an existing language to edit it, or add a new one
4. Configure Detection: Set the following fields:
   • Extensions: File extensions that should use this language (e.g., cs for C#, rs for Rust)
   • Filenames: Specific filenames without extensions (e.g., Makefile, .bashrc, .zshrc)
   • Grammar: The syntax highlighting grammar to use (must match a grammar name from syntect)

Example: Adding Shell Script Detection for Dotfiles

To make Fresh recognize .bashrc, .zshrc, and similar files as shell scripts:

1. Open Settings (Edit → Settings...)
2. Go to Languages → bash (or create a new bash entry)
3. Add filenames: .bashrc, .zshrc, .bash_profile, .profile
4. The grammar should be set to Bourne Again Shell (bash) or similar

Fresh checks filenames first, then extensions, allowing dotfiles without traditional extensions to get proper syntax highlighting.