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10 May 2015

Wonderful answer to "What is the appeal of dynamically-typed languages?"

Erik Osheim's post, "What is the appeal of dynamically-typed languages?", is one of the best explanations of the value of dynamic languages that I've ever read. This is the kicker for me:

One advantage Python has is that this same faculty that you are using to create a program is also used to test it and debug it. When you hit a confusing error, you are learning how the runtime is executing your code based on its state, which feels broadly useful (after all, you were trying to imagine what it would do when you wrote the code).

By contrast, writing Scala, you have to have a grasp on how two different systems work. You still have a runtime (the JVM) which is allocating memory, calling methods, doing I/O, and possibly throwing exceptions, just like Python. But you also have the compiler, which is creating (and inferring) types, checking your invariants, and doing a whole host of other things. There's no good way to peek inside that process and see what it is doing. Most people probably never develop great intuitions around how typing works, how complex types are encoded and used by the compiler, etc.

This logic also explains why Go is so easy to write and probably accounts for its astounding rate of adoption. It's so much easier to master both the running Go language and its type system compared to other statically typed languages.

Erik's answer also puts last year's popular posts, "Why Go Is Not Good" and "Go's Type System Is An Embarrassment", in perspective. The authors of those posts don't appreciate how many people have trouble understanding complex type systems. A lack of understanding prevents programmers from using such languages effectively, which reduces overall adoption.
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