The groupBy Function In DataWeave Mule 4
This function is useful for grouping together items in an array based on some value that is generated from each item in the array.
The distinctBy Function In DataWeave Mule 4
This function is useful for when you need to remove duplicate items from an Array.
The map Function In DataWeave Mule 4
Iterates over items in an array and outputs the results into a new array.
The filter Function (and Function Type Signatures) In DataWeave Mule 4
This function can be applied to an array. It iterates the array and matches the values with the expression. The output of the filter function is an array with the matching values.
Arrays (dw::core::Arrays)
DataWeave 2.0 makes it easier to define an array with a range (" to ").
$, $$, $$$ Syntax
For functions that DataWeave provides, you can represent the first, second, and third arguments of the passed lambda as $, $$, and $$$, respectively. When you do this, you do not need to specify the arguments of the lambda when you pass it to the function.
Infix Notation
This type of notation is referred to as infix since the operator is in between the two operands that it is working on.
Functions as Values
In other words, lambdas become useful when you want to pass functions as arguments to other functions, or return a function from a function.
Lambdas Function
DataWeave provides multiple ways to create functions. Just like we have named functions, we have functions without names, called lambdas.
Named Functions
We create functions in the declarations section of the script using the fun keyword. This associates a set of functionality with a name.