How to write an expression rule that returns multiple values?

Just an aside...in a future release of Appian you'll be able to return data in 'map' format (this is already generated from a Decision Rule if you have multiple outputs of different data types) but you'll have access to the a!map() function natively, as per the following example:

a!map(
  myInteger: 99,
  myString: "Ipsum Lorem",
  myDecimal: 3.14159,
  myBoolean: true,
  myIntegerList: {3,5,7,9}
)

The above code returns the following output:

This will bust the current limitation where Expression Rules can only return one 'type' of data as their final result.

What will be the difference to the "{}" dictionary?

+1, curious what benefits this offers compared to essentially returning an "any type" dictionary.

That when extracting the values from the map the value won't be wrapped in a variant but will be natively of the type expected:

{
  myInteger: 99,
  myString: "Ipsum Lorem",
  myDecimal: 3.14159,
  myBoolean: true,
  myIntegerList: {3,5,7,9}
}.myInteger

returns:

whereas:

a!map(
  myInteger: 99,
  myString: "Ipsum Lorem",
  myDecimal: 3.14159,
  myBoolean: true,
  myIntegerList: {3,5,7,9}
).myInteger

returns:

According to the feature description:

"[this]...will help to reduce unexpected errors in your interfaces and rules. Maps will simplify your expressions and make it easier to work with other types."

oh, that sounds great then - i can finally get rid of this nervous twitch i've developed over time by being caught off guard by weird type mismatches

Hah, likewise! I can't promise you which release of Appian it'll arrive in but it's in progress.

Really nice little feature!

Really nice little feature!