The expression feature is now available in beta as a native Rule Engine feature! If you’re part of our beta program, you should be able to see the post in the beta category.
If you’re not part of the beta program, you can use the /math endpoint noted above or send a PM to @support with your math/date expression use-case and we can get you added to the beta group!
Using a variable that contains an array will no longer “pretty print” arrays as the new expression feature enables custom formatting.*