Check out my new course Learn you some Lambda best practice for great good! and learn the best practices for performance, cost, security, resilience, observability and scalability.
C# developers should be familiar with the yield keyword that was introduced in C# 2.0, and you’ll be pleased to know that F# also has the yield keyword which works in conjunction with F#’s equivalent of IEnumerable – sequences.
You can create sequences in F# using sequence expressions:
In addition, you can also use the yield! (pronounced yield bang) keyword to return a subsequence which is merged into the final sequence. Using a rather contrived example (sorry…) let’s compare the output of yield and yield!:
Look at how the signatures differ for these two sequences:
and how the values in the two sequences differ too:
The yield! keyword is similar to IEnumerable.SelectMany in its ability to flatten a collection of collections but it’s far more powerful as you can mix and match it with other yield/yield! statements and give you a level of expressiveness that IEnumerable.SelectMany does not.
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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.
- Lambda optimization tip – enable HTTP keep-alive
- You are thinking about serverless costs all wrong
- Many faced threats to Serverless security
- We can do better than percentile latencies
- I’m afraid you’re thinking about AWS Lambda cold starts all wrong
- Yubl’s road to Serverless
- AWS Lambda – should you have few monolithic functions or many single-purposed functions?
- AWS Lambda – compare coldstart time with different languages, memory and code sizes
- Guys, we’re doing pagination wrong