Assemble string in DataWeave 2.x (efficiently)

Question

I wanted to write a function in DataWeave (DW 2.0, Mule Runtime 4.3) that could decorate a text message with a banner of * around it, mostly to help call out events in the log.

What I came up with was this, but it feels a little bit Rube Goldberg still. So is there a much more efficient way to write this that I've overlooked?

%dw 2.0
output text/plain
var msg = "WT 3-4"

fun banner(in) =
    do {
        var width = sizeOf(in) + 4
        var standout = 1 to (width) map "*" joinBy ""
        ---
        standout ++ "\n* " ++ in ++ " *\n" ++ standout
    } 
---
//banner ("Hello World")
banner (msg)

This gives me:

***************
* Hello World *
***************

and

**********
* WT 3-4 *
**********

respectively.

My objections to this are many, but this question is primarily about the construction of the banner strings.

var standout = 1 to (sizeOf(in) + 4) map "*" joinBy ""

There HAS to be a better way to arithmetically assemble a string than using map() and joinBy() on the width parameter.

Right?

Answer 1

Well, that is embarrassing. When this idea is refactored for string interpolation and the use of the right tool, the answer looks much better.

%dw 2.0
output text/plain

import repeat from dw::core::Strings
var msg = "Read the Release Notes!"

fun banner(in) =
    do {
        var width = sizeOf(in) + 4
        var standout = repeat("*", width)
        ---
        "$(standout)\n* $(in) *\n$(standout)"       
    }
    
---
banner(msg)

The highly apt output then becomes:

***************************
* Read the Release Notes! *
***************************