It's possible that you have themes or grammars from TextMate that you like and use and would like to convert to Atom. If so, you're in luck because there are tools to help with the conversion.
Converting a TextMate bundle will allow you to use its editor preferences, snippets, and colorization inside Atom.
Let's convert the TextMate bundle for the R programming language. You can find other existing TextMate bundles on GitHub.
You can convert the R bundle with the following command:
apm init --package language-r --convert https://github.com/textmate/r.tmbundle
You can now change directory into language-r to see the converted bundle. Once you link your package with the apm link command, your new package is ready to use. Launch Atom and open a .r file in the editor to see it in action!
This section will go over how to convert a TextMate theme to an Atom
theme.
TextMate themes use plist files while Atom themes use CSS or Less to style the UI and syntax in the editor.
The utility that converts the theme first parses the theme's plist file and then creates comparable CSS rules and properties that will style Atom similarly.
Download the theme you wish to convert, you can browse existing TextMate themes on the TextMate website.
Now, let's say you've downloaded the theme to ~/Downloads/MyTheme.tmTheme, you can convert the theme with the following command:
apm init --theme my-theme --convert ~/Downloads/MyTheme.tmTheme
You can then change directory to my-theme to see the converted theme.
Once your theme is installed you can enable it by launching Atom and opening the Settings View with the Atom > PreferencesFile > PreferencesEdit > Preferences menu item. Then select the "Themes" tab on the left side navigation. Finally, choose "My Theme" from the "Syntax Theme" dropdown menu to enable your new theme.
Your theme is now enabled, open an editor to see it in action!