array to text

In answer to your first question you can use fn!joinarray():

fn!joinarray(
  a!localVariables(
    local!data1: { "test1<br>", "test2<br>" },
    local!data1
  )
)

If you want to have the output actually on separate lines (as is indicated by your second question) then you can loop through your input items and append a "new line" Unicode character to all items except the last item:

a!localVariables(
  local!myList: { "Test1", "Test 2", "Test 3" },
  local!myResult: fn!joinarray(
    a!forEach(
      items: local!myList,
      expression: if(
        fv!isLast,
        fv!item,
        concat(fv!item, char(10))
      )
    )
  ),
  { a!paragraphField(value: local!myResult) }
)

In answer to your first question you can use fn!joinarray():

fn!joinarray(
  a!localVariables(
    local!data1: { "test1<br>", "test2<br>" },
    local!data1
  )
)

If you want to have the output actually on separate lines (as is indicated by your second question) then you can loop through your input items and append a "new line" Unicode character to all items except the last item:

a!localVariables(
  local!myList: { "Test1", "Test 2", "Test 3" },
  local!myResult: fn!joinarray(
    a!forEach(
      items: local!myList,
      expression: if(
        fv!isLast,
        fv!item,
        concat(fv!item, char(10))
      )
    )
  ),
  { a!paragraphField(value: local!myResult) }
)

Maybe it's just me, but this seems like a lot of extra run-around compared to `joinarray(local!list, char(10))` which is equivalent.

You'll get an extra char(10) in your code, which, in the scheme of things, may not be a big deal. I was trying to provide illustrations, not definitive solutions.

...actually, I take that back - joinarray() only inserts the separator between the elements of the array, so no extra char(10) at the end...so yours is indeed the less verbose solution. 

yeah, any extra complexity and you need to know how to do a!forEach() with use of fv!isLast (etc), though for this case I felt like that was putting the cart before the horse a bit ;-)

Thank you.