Most real-world programming languages are too complex to be studied using formal methods. For this reason, academics often work with simple theoretical languages instead. The λ-calculus is a simple formal language that is often used for talking about functional languages, the π-calculus is a model of concurrent programming and there is an entire book, A Theory of Objects modelling various object-oriented systems. Animation from Financial Times article "Why the world's recycling system stopped working". Tho[...]

TL;DR To make an AppSync DynamoDB resolver throw exceptions on conditional check errors, we need to check $context.error in the response mapping template ourselves. Like this: #if ( $ctx.error ) #if ( $ctx.error.type.equals("DynamoDB:ConditionalCheckFailedException") ) $util.error("your error message") #else $util.error($ctx.error.message, $ctx.error.type) #end #end $utils.toJson($context.result) And now, the longer version. The problem AppSync lets us perform DynamoDB … AppSync: how to error on DynamoDB[...]

Have you been wondering about serverless but just don’t know how and where to start? Maybe you’re already building stuff with serverless, but don’t know if you’re doing it right? Are you unsure about the best practices for testing, monitoring and how to choose between similar services like SNS and EventBridge?   I have just … Skill up your serverless game with my new instructor-led online workshop Read More » Liked this article? Support me on Patreon and get direct help from me via a private Slack chann[...]

So you have built a serverless application, that, amongst other things, lets you upload images and files to S3. The set-up is very simple: API Gateway, Lambda and S3. It took you no time to implement and it works like a dream. You pat yourself on the back for another job well done. Until one … Hit the 6MB Lambda payload limit? Here’s what you can do. Read More » Liked this article? Support me on Patreon and get direct help from me via a private Slack channel or 1-2-1 mentoring. Hi, my name is Yan C[...]

Despite having the term science in its name, it is not always clear what kind of discipline computer science actually is. Research on programming is sometimes like science, sometimes like mathematics, sometimes like engineering, sometimes like design and sometimes like art. It also has a long tradition of importing ideas from a wide range of other disciplines. In this article, I will look at ideas from architecture and urban planning. Architecture has already been an inspiration for design patterns, althou[...]