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Local Golang playground MELPA Stable MELPA

A simple mode for GNU/Emacs to set up a local Go language playground, offering features similar to — and in some ways surpassing — the play.golang.org service, thanks to go-mode. Treat it as a simple REPL for Go. Unlike play.golang.org, this mode provides a complete local playground within Emacs, eliminating the need for a browser or even internet connection to experiment with code snippets.

While the web playground at play.golang.org is convenient, it comes with restrictions, especially when using additional tools like linters and code completers. Emacs excels in providing these tools for Go development, making it more comfortable to work with snippets directly within Emacs. Setting up a local playground does require configuring the Go environment, but this is necessary for Go development regardless.

Features

  • Utilizes go-mode with all your plugins (like lsp, linters, etc.)
  • Allows importing external packages
  • Maintains a library of snippets under a customizable root path
  • Supports multiple source files (or subpackages) for a snippet
  • Compatible with Go modules

Install

First, install go-mode and gotest — these are mandatory. Set up any additional tools you need for Go development (see the Emacs Wiki or search for "emacs+golang"). A minimal setup includes goimports, which automatically adds import clauses to your snippets. For a fully functional Go IDE, consider using lsp and supplementary packages.

Install go-playground from MELPA:

M-x package-install RET go-playground

Or:

(use-package go-playground)

To share snippets, use go-play-buffer from go-mode. Install gist-buffer from MELPA if you want to publish gists on github.com.

Usage

Quick start

  1. Run M-x go-playground to start a new playground buffer filled with a basic template for the main package (see the screenshot below).
  2. Add your code and press Ctl-Return (bound to go-playground-exec), which saves, compiles, and executes the snippet.
  3. To remove the current snippet and its directory, run M-x go-playground-rm.

List of interactive functions

Function name Bound Description
go-playground Create a new playground buffer with a basic template for the main package.
go-playground-download Download a snippet from a URL at play.golang.org.
go-playground-exec C-c C-c Save, compile, and run the snippet's code.
go-playground-cmd C-u C-c C-c Save the code and prompt for a command (compile-mode used).
go-playground-upload Upload the buffer to play.golang.org and return the short URL.
go-playground-rm Remove the snippet with its directory and all files.

The mode sets default bindings only for two commands, leaving space for your customizations.

List of customizable variables

Variable name Description
go-playground-ask-filename Ask for the snippet filename on a new playground creation. By default, it's named snippet.go.
go-playground-basedir Default directory for storing snippets. Each new snippet is placed in a new directory under this path. Place it under GOPATH for organization. Introduced in release 1.1.
go-playground-confirm-deletion Confirm before deleting a snippet. You can disable this if it's annoying. Introduced in release 1.2.
go-playground-compile-command Customize the compiler command or run additional commands. Default is "go mod tidy; go run ./...".
go-playground-init-command Shell command to run once when a new snippet is created.
go-playground-compiler-args Arguments passed to the compiler.
go-playground-pre-rm-hook Hook to run before a snippet is removed.

Example screen after creating a new snippet:

screenshot

Using with lsp-mode

If you use lsp-mode, add a hook to clean up the workspace when a snippet is removed, like this:

(defun my/go-playground-remove-lsp-workspace () (when-let ((root (lsp-workspace-root))) (lsp-workspace-folders-remove root)))
(add-hook 'go-playground-pre-rm-hook #'my/go-playground-remove-lsp-workspace)

Snippets with Multiple Files and Subpackages

See Issue #19 for details.

Similar projects

  • go-scratch is simpler but restricts tool usage by not keeping code in files.
  • gorepl-mode is a REPL for Go, useful for interactive code research.

License

Under terms of GPL v3. See LICENSE file.

Future plans and accepting contributions

I aim to keep this package simple, leveraging other packages around go-mode. Bugfixes and small features are welcome.