You can become a serverless blackbelt. Enrol to my 4-week online workshop Production-Ready Serverless and gain hands-on experience building something from scratch using serverless technologies. At the end of the workshop, you should have a broader view of the challenges you will face as your serverless architecture matures and expands. You should also have a firm grasp on when serverless is a good fit for your system as well as common pitfalls you need to avoid. Sign up now and get 15% discount with the code yanprs15!
Having spent a bit of time learning the basics of F# I decided to try my hands on actually writing some code and get a better feel of the language and get more used to writing function code in general. And for that purpose, Project Euler provides a great source for small, isolated problems well suited for a functional language like F#.
As of today there are a total of 300 questions, ordered in such a way that they’re progressively more difficult to solve, and whilst I’ll be posting my own answers written in F# you could just as easily solve these problems in a variety of languages.
So back to the first problem, here’s the brief:
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
Find the sum of all the multiples of 3 or 5 below 1000.
Here’s a one liner solution in F#:
let total = [1..999] |> List.map (fun i -> if i % 5 = 0 || i % 3 = 0 then i else 0) |> List.sum
Let me break down the solution a little, and go through it step by step.
I started off with [1..999] which is one of many ways you can create and initialize a new list in F#, doing this gives me a list with the values 1, 2, 3, … 998, 999, i.e. all the natural numbers below 1000.
|> is known as the forward pipe operator, it allows you to pass the result of the left side of the operator to the function on the right side. For a C# developer it is perhaps easier to simply think of it as chaining a couple of methods in a Linq query, e.g.
var total = Enumerable.Range(1, 999).Select(x => x % 3 == 0 || x % 5 == 0 ? x : 0).Sum();
The List.map function lets you apply a function to each element of a list and put all the results into a new list, as you’ve seen from the above C# code, it provides the same projection capability you get with the Enumerable.Select method in Linq.
In this particular case, I’m simply saying “for each element in the list, return the element if it’s a multiple of 3 or 5, otherwise return 0”, whilst this does not filter out the elements that are not multiples of 3 or 5 the final List.sum will simply ignore the zeros returned from the previous function.
You could equally use a predicate to filter out the elements which are not multiples of 3 or 5:
let total = [1..999] |> List.filter (fun i -> i % 5 = 0 || i % 3 = 0) |> List.sum
Hi, I’m Yan. I’m an AWS Serverless Hero and I help companies go faster for less by adopting serverless technologies successfully.
Are you struggling with serverless or need guidance on best practices? Do you want someone to review your architecture and help you avoid costly mistakes down the line? Whatever the case, I’m here to help.
Skill up your serverless game with this hands-on workshop.
My 4-week Production-Ready Serverless online workshop is back!
This course takes you through building a production-ready serverless web application from testing, deployment, security, all the way through to observability. The motivation for this course is to give you hands-on experience building something with serverless technologies while giving you a broader view of the challenges you will face as the architecture matures and expands.
We will start at the basics and give you a firm introduction to Lambda and all the relevant concepts and service features (including the latest announcements in 2020). And then gradually ramping up and cover a wide array of topics such as API security, testing strategies, CI/CD, secret management, and operational best practices for monitoring and troubleshooting.
If you enrol now you can also get 15% OFF with the promo code “yanprs15”.
Check out my new podcast Real-World Serverless where I talk with engineers who are building amazing things with serverless technologies and discuss the real-world use cases and challenges they face. If you’re interested in what people are actually doing with serverless and what it’s really like to be working with serverless day-to-day, then this is the podcast for you.
Check out my new course, Learn you some Lambda best practice for great good! In this course, you will learn best practices for working with AWS Lambda in terms of performance, cost, security, scalability, resilience and observability. We will also cover latest features from re:Invent 2019 such as Provisioned Concurrency and Lambda Destinations. Enrol now and start learning!
Check out my video course, Complete Guide to AWS Step Functions. In this course, we’ll cover everything you need to know to use AWS Step Functions service effectively. There is something for everyone from beginners to more advanced users looking for design patterns and best practices. Enrol now and start learning!
Here is a complete list of all my posts on serverless and AWS Lambda. In the meantime, here are a few of my most popular blog posts.
- All you need to know about caching for serverless applications
- Lambda optimization tip – enable HTTP keep-alive
- You are wrong about serverless and vendor lock-in
- You are thinking about serverless costs all wrong
- Just how expensive is the full AWS SDK?
- Check-list for going live with API Gateway and Lambda
- How to choose the right API Gateway auth method
- CloudFormation protip: use !Sub instead of !Join
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- Guys, we’re doing pagination wrong
- Top 10 Serverless framework best practices
- How to break the “senior engineer” career ceiling
- My advice to junior developers