[rleisti]

One of the things that a 'dynamic' type system (or as the author would see it, a restriction to a single type) imposes on its creators is the need to make that single type as useful as possible. This includes things like being able to easily lookup an object's class, documentation, methods, properties, uses (is it a sequence? is it a map?, etc.). As a result, I find the design of the core libraries of dynamic languages like Clojure more well thought-out than say something like .NET. It's simple things like being able to treat a string as a sequence (Haskell, a statically-typed language, does this), an 'object' as a map, a map as a sequence, etc. I wonder if it has to do with a sort of de-centralization of control; being dynamic seems to make a language more malleable and open to experimentation. Accomplishing the same things in a statically-typed language requires more planning (which means that after it ships, its too late).

I really appreciate a well-thought out static language like Haskell, but it still has some way to go for the common programmer. For now, I don't think that the practical outcome of this article is for programmers to abandon dynamic languages.

[TimJYoung]

"This includes things like being able to easily lookup an object's class, documentation, methods, properties, uses (is it a sequence? is it a map?, etc.)."

Most decent OO, statically-typed compilers allow for runtime type information. Delphi (native) and the .NET compilers allow you to query all sorts of information about a given object instance, including its class name, properties, methods, etc. Here's some links on Delphi's native compiler RTTI and attributes:

http://stackoverflow.com/questions/2217068/why-should-i-care...

http://robstechcorner.blogspot.com/2009/09/so-what-is-rtti-r...

Object instances in environments like .NET and Delphi are inherently dynamically-typed.

Statically-typed languages provide the safety of checking the "stupid stuff" during compilation without sacrificing the flexibility of using dynamic types in the form of classes. And many do so without any major compilation overhead (Delphi and .NET compilers are very fast).

[regularfry]

You could do that sort of classless message passing in a static language. In fact, isn't that how message dispatch in Obj-C works?

[lloeki]

The only statically typed part of Obj-C is the C part, while the Obj-C types are themselves dynamic.