Does “untyped” also mean “dynamically typed” in the academic CS world?

Question

I\'m reading a slide deck that states \"JavaScript is untyped.\" This contradicted what I thought to be true so I started digging to try and learn more.

Every answer

Answer 1

Agree with Brendan - context is everything.

My take:

I remember being confused, circa 2004, because there were arguments breaking out about whether Ruby was untyped or dynamically typed. Old school C/C++ people (of which I was one) were thinking about the compiler and saying Ruby was untyped.

Remember, in C, there are no runtime types, there are just addresses and if the code that's executing decides to treat whatever's at that address as something it isn't, whoops. That's definitely untyped and very different from dynamically typed.

In that world, "typing" is all about the compiler. C++ had "strong typing" because the compiler's checks were more stringent. Java and C were more "weakly typed" (there were even arguments about whether Java was strongly or weakly typed). Dynamic languages were, in that continuum, "untyped" because they had no compiler type checking.

Today, for practicing programmers, we're so used to dynamic languages, we obviously think of untyped to mean no compiler nor interpreter type-checking, which would be insanely hard to debug. But there was a period there where that wasn't obvious and in the more theoretical world of CS is may not even be meaningful.

In some deep sense, nothing can be untyped (or almost nothing, anyway) because you must have some intent in manipulating a value to write a meaningful algorithm. This is the world of theoretical CS, which isn't dealing with the specifics of how a compiler or interpreter is implemented for a given language. So "untyped" is (probably, I don't know) entirely meaningless in that context.