How can we convert Mule 4 datawevae 2.0 code to Mule 3 dataweave 1.0?

Question

I have the following dataweave 2.0 code in Mule 4 and I need this code in Mule 3 dataweave 1.0. Can someone help me how to convert this code to dw 1.0?

    Dataweave step 1

%dw 2.0
output application/json
fun prepareList(list:Array, maxSize: Number) = if(sizeOf(list) >= maxSize )
list
else
prepareList(list ++ [(sizeOf(list) + 1) as Number],maxSize)
---
(payload map (row, index) -> ({
    dummy : prepareList([],sizeOf(row))  map (irow, icounter) -> {

        ((row[icounter] splitBy "=")[0]) : (row[icounter] splitBy "=")[1] 
    } 

})) 



Dataweave step 2

%dw 2.0
output application/json
---
((payload reduce ((item, acc) -> acc ++ item)).*dummy map (row, index) -> ({
    index : row reduce ((item2, acc2) -> acc2 ++ item2)
})).*index

Answer 1

Most of the operations like map, reduce, splitBy will work mostly the same in DataWeave 1.0 and probably require little or no change. The * selector is the same.

You will have to replace if...else... by when...otherwise...

You will also have to change the declarations before the --- divider to match the DataWeave 1.0 conventions.

Example:

%dw 1.0
%output application/json
%function prepareList(list, maxSize) 
              list when ( sizeOf(list) >= maxSize ) 
                   otherwise prepareList(list ++ [(sizeOf(list) + 1) as Number],maxSize)
---

Answer 2

You cannot. It looks similar but DW 2 is much more powerful than DW 1. It is like changing C++ to C. Looks the same but concepts are different.

It is true for opposite way. https://simpleflatservice.com/mule4/Mule3toMule4Transformation.html