Lambda the Ultimate

I just noticed this project and since we like discussing language-in-a-language projects, I thought I'd mention it.

It seems that they are almost ready to run Rails. Now that's going to be cool!

An idea occurred to me the other day, and I was wondering if anyone has seen anything like it. I'm sure I can't be the only one to have thought of this. The idea is to take the type annotations that we normally have in statically typed programs and place them in a separate file. A program in a language which allows this would look like it was dynamically typed, but static typing could be added progressively by adding declarations in a separate file. A good IDE could present a merged view of the source.

The thought behind this is that languages seem to mix two concerns in the program text: 1) the form of the program, and 2) an error detection regimen enforced by the compiler. It seems that they could be decoupled. A piece of program text could, for instance, have one set of types in one program, and another set of types in another.

Note that this has nothing to do with type inferencing. The idea is do to this for a "run of the mill" dynamically typed language.

Here's a link to a blog describing the idea.

I apologize for the lame attempts at entertainment at the beginning of the blog. They, regretfully, obscure my point a bit.