$$reduce

Reduce an array with an initial value (identity) and a context transformer to a single value.

Usage

{
  "$$reduce": [ /* values */ ],
  "identity": /* initial value */,
  "to": /* Transformer */
}

Returns

Type of to's result or identity's

Arguments

Argument	Type	Values	Required / Default Value	Description
Primary	array		Yes	Array of elements
to	Transformer(##accumulator,##current,##index)	Input is ##accumulator (previous accumulator value), ##current (current element) & ##index (current index)	Yes	Transformer to apply on each element (with last accumulation) to get the next accumulation
identity			Yes	Initial value to start the accumulation with

Examples

Input

Definition

Output

[
  {
    "amount": 10
  },
  {
    "amount": 20
  }
]

{ 
  "$$reduce":"$", 
  "to": "$$math(##accumulator,+,##current.amount)", 
  "identity": 1 
}

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