How to update the array inside the for each loop and to use the updated value in further iteration?

Hi,

I have a requirement to update the actual array value and the updated values in the array I need to use it in my further iterations in a for loop, for eg., below is the sample code for my requirement

a!localVariables(
local!arrayToLoop: {
{credit: 10, debit: 100, txn1: 0, txn2: 150, txn3: 0},
{credit: 100, debit: 0, txn1: 0, txn2: 150, txn3: 0},
{credit: 0, debit: 100, txn1: 0, txn2: 150, txn3: 0},
{credit: 0, debit: 100, txn1: 0, txn2: 150, txn3: 0},
{credit: 0, debit: 0, txn1: 0, txn2: 150, txn3: 0},
{credit: 75, debit: 80, txn1: 0, txn2: 150, txn3: 0},
{credit: 65, debit: 0, txn1: 0, txn2: 150, txn3: 0},
{credit: 0, debit: 100, txn1: 0, txn2: 150, txn3: 0},
{credit: 50, debit: 70, txn1: 0, txn2: 150, txn3: 0},
{credit: 40, debit: 100, txn1: 0, txn2: 150, txn3: 0}
},
a!foreach(
items: local!arrayToLoop,
expression: if(
fv!isFirst,
fv!item,
if(
tointeger(
fv!item.credit
) > 0,
fv!item,
updatecdt(
fv!item,
{
credit: index(
local!arrayToLoop.credit,
fv!index - 1,
0
)
}
)
)
)
)
)

Output of the above code is 

[credit:10,debit:100,txn1:0,txn2:150,txn3:0]; [credit:100,debit:0,txn1:0,txn2:150,txn3:0]; [credit:100,debit:100,txn1:0,txn2:150,txn3:0]; [credit:0,debit:100,txn1:0,txn2:150,txn3:0]; [credit:0,debit:0,txn1:0,txn2:150,txn3:0]; [credit:75,debit:80,txn1:0,txn2:150,txn3:0]; [credit:65,debit:0,txn1:0,txn2:150,txn3:0]; [credit:65,debit:100,txn1:0,txn2:150,txn3:0]; [credit:50,debit:70,txn1:0,txn2:150,txn3:0]; [credit:40,debit:100,txn1:0,txn2:150,txn3:0]

Here in my current code the actual array is not getting updated, only the fv!item is getting updated so when I check the the "credit" value of the previous ideration it is still "0" as per the original array

But the expected outout is 

[credit:10,debit:100,txn1:0,txn2:150,txn3:0]; [credit:100,debit:0,txn1:0,txn2:150,txn3:0]; [credit:100,debit:100,txn1:0,txn2:150,txn3:0]; [credit:100,debit:100,txn1:0,txn2:150,txn3:0]; [credit:100,debit:0,txn1:0,txn2:150,txn3:0]; [credit:75,debit:80,txn1:0,txn2:150,txn3:0]; [credit:65,debit:0,txn1:0,txn2:150,txn3:0]; [credit:65,debit:100,txn1:0,txn2:150,txn3:0]; [credit:50,debit:70,txn1:0,txn2:150,txn3:0]; [credit:40,debit:100,txn1:0,txn2:150,txn3:0]