Someone shared Charles Scalfani’s article about why they were abandoning Object Oriented Programming and moving to Functional Programming. The points Charles makes are:

• Inheritance and hierarchies tend to be fragile and difficult to work with;
• Making variables private in an object doesn’t help that much; and
• Polymorphism isn’t exclusive to OOP;

These experiences probably resonate with many people who’ve worked with OOP codebases. In any language. So I’m not going to say that Charles is wrong, but I’d like to offer a different perspective of the ideas in OOP here. And maybe that’ll help someone learn something new in the process, who knows?

Most programming languages should have a concept similar to effect handlers, even if the language doesn’t include an effect system as well. One reason for this is simply that they’re a cool feature, but the important part is that effect handlers solve a very real tension between programmer intent and execution context, which shows in testing, cross-platform development, distributed computing, and several other common cases.

This piece will briefly discuss what they are, what problems they solve, and how they solve it. For a more detailed treatise of the subject, see Pretnar’s effect handlers tutorial.