DataWeave 2  Generate Fibonacci sequence
In this post, we will see how to generate a Fibonacci sequence using DataWeave 2.
Fibonacci Sequence
Fibonacci number sequence is a series of numbers where each number is the sum of two preceding ones, starting from 0 and 1.
Generating Fibonacci sequence in DataWeave
We can generate Fibonacci sequence in DataWeave with a simple recursive function.
Script  Output (application/json) 

%dw 2.0 output application/json indent=false fun fibonacci(limit:Number,series:Array<Number>) (1) = if (limit <= 0) series else fibonacci( limit  1, series + (series[1] + series[2])) fun fibonacci(limit:Number) = fibonacci(limit, [0, 1]) (2)  { limit10: fibonacci(10), (3) limit15: fibonacci(15, [13,21]) (4) } 
{ "limit10": [0,1,1,2,3,5,8,13,21,34,55,89], (5) "limit15": [13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765,10946,17711,28657] (6) } 
1  fibonacci function computing the sequence with a given number count limit. 
2  Overloaded fibonacci function to start with default 0 and 1 as starting. 
3  Get 10 fibonacci sequence numbers start from default 0 and 1 
4  Get 15 fibonacci sequence numbers after 13 and 21 sequential pair 
5  Generated fibonacci for 10 numbers 
6  Generated fibonacci for 15 numbers starting after 13 and 21 
fibonacci
function uses a tailrecursion approach to avoid running into recursion stack limit. It keeps calling itself by decreasing the limit by 1 and adding a new number at the end of series. New number is calculated as sum of the preceding two numbers  Hence the Fibonacci sequence output.
fun fibonacci(limit:Number,series:Array<Number>)
= if (limit <= 0) series
else fibonacci( limit  1, series + (series[1] + series[2]))
What is 103rd number in a Fibonacci sequence? Try running fibonacci(100) using above function. Hint: It is a 21digit number :).

Conclusion
That’s all for this short post. It is not so difficult to write different functions in DataWeave 2. Hopefully, you learned something new here.
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