"Making Impossible States Impossible" by Richard Feldman

"Making Impossible States Impossible" by Richard Feldman [VIDEO] Really changed how I think about programming.

The type system is a lot more expressive than the ones found in Java/C#/C++, thanks to Algebraic Data Types. Yaron Minsky (Jane Street, largest OCaml user) coined the term "make invalid states unrepresentable" to explain how ADTs help in enlisting the help of the compiler to help us express our intent correctly, and Richard Feldman (NoRedInk, largest Elm user) has given an absolute gem of a talk that dives into that idea with relatable, concrete examples. It is titled "Making Impossible States Impossible" and should clarify this concept nicely. [VIDEO]

Making impossible states impossible" by Richard Feldman: [VIDEO] has really changed the way I approach dealing with data in my code and was very insightful.

highly recommend the talks "making impossible states impossible" and "make data structures" by richard feldman. [VIDEO] [LINK] the talks are geared towards elm but I think they offer some great advice applicable to programming in general.

one of my favorite talks on this topic, "Making Impossible States Impossible" by Richard Feldman: [VIDEO] the talk is Elm lang focused, but the concepts still apply to other languages.

There's a great talk on this subject by Richard Feldman from Elm Conf. I haven't used typescript so I'm not sure if the techniques translate well. [VIDEO]

There is no escaping the mapping. It doesn't matter if it is Reason or PureScript, Elm, or Fable - you have to parse the incoming data into a static type if you want to enjoy the benefits of types. The good thing is that you can build the rest of your system with a firm guarantee on the shape and structure of the data. No null checks, no missing keys. If you are careful with your parsing you can raise exceptions or return None if the incoming data is not well-formed (missing keys or even extra keys). Reason/BuckleScript when run on a Javascript runtime also has a `Js.t` type which is basically the Javascript object. You do have to define the shape of it similar to how you'd define a record type, but you don't need to convert it into a native record. JS arrays are also natively supported - it maps 1:1 to BuckleScript's array. I like to convert arrays into lists since they are better suited for value-based programming (pattern-matching over [head, ...tail] inside recursive functions). And if you create your types in a way that invalid states are impossible, you've just reduced the cognitive load needed to work on the system for the rest of its life by an order of magnitude. Here are some resources on this wonderful programming technique: - [LINK] - [VIDEO] - [LINK] - [LINK]

That'll be a great addition to the book. Can I also recommend Yaron Minsky's talk on OCaml, specifically the part where he talks about "making invalid states impossible": [LINK] I've found this to be the single most valuable programming technique I've learnt. Richard Feldman dives deeper into the topic with a lot more examples in [VIDEO]