Type-Safety

Two years ago (!!!) I published a post on discourse.dry-rb.org explaining my plans for dry-validation 1.0.0 and in this post I mentioned that there will be a new gem called dry-schema that dry-validation will use for its schemas. It’s crazy how time flies because I swear I thought it was last year. I know that over this time dry-validation has been accumulating a lot of issues (125 in the moment of writing this article), and I know it sucks, big time, that I didn’t have a chance to address any of these. ...

Duck typing is one of the virtues of the Ruby language, it adds a lot of flexibility to the code, and allows us to use objects of different type in places where only specific methods are needed. Even though the idea behind duck typing may seem to be straight-forward, it is easy to use it incorrectly. It’s interesting to notice that over many years we’ve adopted various techniques that seem to leverage duck typing, but the specifics of how exactly we’re doing it are actually questionable, and I believe they deserve some reconsideration. This is directly related to the other important subject - type safety, and in this article I’d like to explain why we should care about it, while keeping duck typing in mind, too. ...

The idea of an object that validates its own state has been made very popular by Rails’ ActiveRecord. We can see this pattern in many places, not only in ORM libraries but in many other gems whenever some sort of validation is needed. Have you ever thought about why we’re allowing invalid state just to…validate data? It doesn’t seem to be a good idea, in fact, it feels like a huge anti-pattern. ...