How to create snippets in Helix?

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How to create snippets in Helix?

2023-07-31

Helix currently does not support snippets. However, there is a workaround to insert snippets using :insert-output to run a shell command. Still, this might not feel like the most natural way to work with snippets.

For instance, in GoLand, a similar feature called live templates allows you to type err and expand it into the following:

if err != nil {
  
}

I wonder if I can archieve the same functionality in Helix by creating a simple language server using the Language Server Protocol.

After exploring different SDKs for the LSP I decided to give go-lsp a try, as I am most familiar with Golang.

Here’s what I came up with. Initially, I encountered and error during the first attempt:

{
  "jsonrpc": "",
  "id": 0,
  "result": {
    "capabilities": {
      "textDocumentSync": 1,
      "completionProvider": {
        "triggerCharacters": [
          "."
        ]
      }
    }
  },
  "error": null
}

2023-07-31T17:12:56.162 helix_lsp::transport [ERROR] snippets-ls err: <- Parse(Error("data did not match any variant of untagged enum ServerMessage", line: 0, column: 0))

However, I was able to resolve the issue by passing the jsonrpc version in the response.

To test this feature, you can create a configuration file like this:

main: |-
  func main() {
      $1
  }

err: |-
  if err != nil {
      $1
  }

Then add the following into ~/.config/helix/languages.toml:

[[language]]
name = "go"
formatter = { command = "goimports"}
language-servers = ["gopls", "snippets-ls"]

[language-server.snippets-ls]
args = ["-config", "/Users/quantong/.config/helix/go-snippets.yaml"]
command="snippets-ls"

Now, when we open a .go file in Helix, the editor forks a process to start the language server:

$ pstree -p 818
-+= 00001 root /sbin/launchd
 \-+= 00440 quantong /Applications/WezTerm.app/Contents/MacOS/wezterm-gui
   \-+= 00487 quantong -fish
     \-+= 00818 quantong hx .
       |--- 00855 quantong /opt/homebrew/bin/gopls
       \--- 00856 quantong /Users/quantong/go/bin/snippets-ls -config /Users/quantong/.config/helix/go-snippets.yaml

Next, you can type err and press tab, Helix will send a textDocument/completion request to the language server:

{
  "jsonrpc": "2.0",
  "method": "textDocument/completion",
  "params": {
    "position": {
      "character": 2,
      "line": 25
    },
    "textDocument": {
      "uri": "file:///Users/quantong/Code/personal/snippets-ls/main.go"
    }
  },
  "id": 3
}

and the server will respond with the result:

{
  "jsonrpc": "2.0",
  "id": 3,
  "result": [
    {
      "label": "main",
      "kind": 15,
      "insertText": "func main() {\n    $1\n}"
    },
    {
      "label": "err",
      "kind": 15,
      "insertText": "if err != nil {\n    $1\n}"
    }
  ],
  "error": null
}

With this setup, you should be able to use snippets in Helix just like in GoLand, enhancing your coding productivity.

Tags: helix lsp golang

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