If the command-line is your thing, you can check out the npm package, which lets you install a pyret command that you can use to compile and run programs.
If you like to use your own editor offline, there are a few options for syntax highlighting:
For Visual Studio Code, just search “pyret” in the extensions explorer.
For Atom, see the instructions at atom-language-pyret.
For Emacs, Sublime, and Vim, check out the tools/ directory in the pyret-lang repository.
To dig into all the details or contribute, can check out the repository on Github: