Static vs Dynamic Typing

This is a summary of arguments and counterarguments I’ve heard in the classic static vs dynamic typing debate. Overall I think this debate doesn’t make a lot of sense. As usual when you’re confronted with a question of X vs Y, the answer is “it depends”.

Claim

This is probably true but…

Dynamic languages are more concise.

Type inference and other language constructs can reduce verbosity.

Compile-time type safety catches errors the programmer missed.

These can be caught with unit tests, and there’s a lot of other things that can go wrong with your program that the compiler can’t catch.

Static languages are more performant.

You can always just scale your hardware and there are plenty of examples of dynamically typed code that’s highly performant.

Dynamic languages let you rapidly prototype, try out new things, fail faster, and build things more quickly.

You can still move reasonably fast with the right expertise, and it may be that moving fast is a lower priority than long-term maintenance.

Statically typed code bases are more maintainable in the long run because types serve as documentation and allow for better tool support.

You can get around this with good design, and it may be that moving fast is a bigger priority than long-term maintenance.

Dynamic languages are simpler to work with. You don’t have to worry about pleasing the compiler so you can just work on your actual problem.

For more sophisticated type systems, the compiler can actually help you prove the correctness of your code.

More sophisticated static type systems like Haskell’s and Ocaml’s actually give you the malleability of dynamic typing without giving up safety.

The complexity burden for developers is much higher.

Other points:

  • You can always build tools to make up for what you lack (like linters).
  • Gradual typing exists, as does the ability to have optional dynamic typing is static languages so it’s not necessarily one or the other.
  • These categories ignore all the nuances within individual languages (i.e. JavaScript vs Python or C++ vs C#) 

Basically the bottom line is that there isn’t a clear winner. There are pros and cons. You have to weigh them out and pick the languages that work best for you and that may even mean a mix of both kinds of languages. There’s no one exact right answer here and that’s part of the fun.