A well-shaven Jim Miller gave a talk at Brown today on introducing dynamic languages into the CLR. I went because (a) they were giving away a free camera (which I didn’t get), and (b) the talk seemed actually interesting. Much more interesting than my last Microsoft talk, which was some interminably boring thing about webservices.

The talk was essentially an overview of the CLR, of the form, “Do you think this is cool? Work for us!” The focus was on IronPython‘s genesis and growth. Those kids love their Python.

I tried to ask him the following question: “You’ve talked a lot about getting basic interoperability between programs written in different languages — object-oriented, procedural, functional — but you’ve said nothing about heterogeneity of styles. How does the CLR cope with that?” I asked because he said that an interface of an object included a way to create it, modify its insides, and so on — not necessarily how I define my datatypes. But then he turned it around, and asked me for an example — the best I could come up with was Erlang’s processes and single-assignment (a red herring) or Haskell’s purity (an academic joke).

Not what I was looking for. The mismatch is more serious, but I couldn’t adequately get at it on the spot. I asked him a follow-up, about GUI programming style. Would a GUI in IronPython need to be written in some bogus Windows Forms style, all callbacks? I didn’t want to compare the callback-GUI system to Flapjax‘s, since that’d be a bit wankerish of me. I didn’t handle it well at all.

So: what did I mean to ask? On the one hand, my problem is this: the mismatch between the CLR and some paradigms is pretty clear. If I wanted to work with Windows Forms in, say, F#, I would have to write in an all-ref style. In other words, the CLR lets me program C# in the language of my choice.

On the other hand, how else would I write a GUI? Flapjax is the most viable FRP implementation I’ve seen, but it’s still extremely nascent. When interfacing with the user, what is better than direct, mutative style? Python uses callback-based Tkinter and WxPython; DrScheme uses the MrEd callback-based framework. So what gives?

I may be more comfortable in the FP world, and happier programming Scheme in Scheme, rather than C# in Scheme, or even worse, Scheme in C# — but it’s becoming increasingly clear to me that my preference may be more related to my own experience than actual advantages.