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Discussion on: Convince me that types are awesome

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Aaron Schlesinger

This is gonna be a really crappy persuasive argument, but I wanted to give pros and cons of types, and you can decide for yourself 😄


  • More self-documenting
    • what does this function expect?
    • how is it gonna use it?
    • what is it gonna return?
  • IDEs can provide richer & faster intellisense / code completion / go to definition / inline docs \
    • Check out XCode for Swift and Visual Studio for C#. Both are 🔥 at this stuff for their languages
  • Usually less boilerplate-ey tests to write
  • Some groups of runtime errors are impossible. Some examples:
    • In some languages, there's a type of array that cannot be empty, so myarray[0] will never throw
    • Others have literally no exceptions. Functions that might fail will always return a type that can either be a successful value, or an error. You have to deal with both or your code won't compile


  • Some typed languages have horrific compiler error messages if you mess up. Good luck figuring out what you did wrong, let alone fixing it
  • Typed languages often have a steeper learning curve
    • There are exceptions on either side, of course!
    • Go is easy to pick up for lots of folks
    • ... and Ruby has magic in it that can trip folks up pretty early on in their learning
  • There's math behind type systems (no joke! "Category Theory" on wikipedia). Some languages will force you to learn some of that, even if they don't mean to
  • Some typed languages have "generics" - being able to write functions that can handle any type. It's handy and powerful, but these functions can be super confusing for the person calling the function

That's all I can think of for now. I think typed languages pay off after you get to a medium sized codebase. I usually reach for them on day 1, because I've been burned a lot by errors in dynamic languages, that typed languages don't have.

Hope this helps!