Expression rule

The requirement is not clear. Share more details.

You can create a rule input of Text type and then pass comma-separated data in that.

Yogi Patel said:

The requirement is not clear.

I like defaulting to the laziest approach possible when the requirements aren't actually spelled out.  For instance, the result here is just a rule that returns "(A1;A2)", without specifying how the rule input (if any) is related to that (and my brain is too fried to try guessing).

So here's my initial rule suggestion:

"(A1;A2)"

Straightforwardness: 10/10.  Flexibility for different rule inputs: ??/10.

Less lazy reply:

let's pretend the rule input is actually 2 inputs, a character and a "times repeated".  I don't feel like writing a parser to accept a comma-separated value when that may have just been OP overly abbreviating what their input is going to be.

a!forEach(
  enumerate(ri!repeats),
  ri!character & fv!index
)

For "A" and 2, that gives us basically their prescribed output:

For "C" and "11", it performs more of the same:

Less lazy reply:

let's pretend the rule input is actually 2 inputs, a character and a "times repeated".  I don't feel like writing a parser to accept a comma-separated value when that may have just been OP overly abbreviating what their input is going to be.

a!forEach(
  enumerate(ri!repeats),
  ri!character & fv!index
)

For "A" and 2, that gives us basically their prescribed output:

For "C" and "11", it performs more of the same: