In Dr. Syme's latest post, A Taste of F# Interactive in Visual Studio, he covers a topic that has been a concern for me: improving the interactive environment for F# beyond the capabilities of competitors like MatLab and Mathematica.

One important feature of a functional programming language is the notion of scope. The scope of my "stuff" in a session has durability for that session. When I run MatLab, my "stuff" is "in the session", unless I explicitly clear it. I can save or load a session, attach useful function libraries, etc., and get stuff done. I interact to spawn other windows for code, plots, environment settings, variable inspection and interaction and so on. While MatLab is not a pure FP, it has many of the characteristics of an FP.

That F# is moving the fsi out of a text based tool and into VS2005 means that I now get some of the benefits that I just mentioned above. Spawn windows for code; check. Plots; check (see the graphic on that post). Environment settings; check (pathing, loading other libraries, etc. was already there). Variable inspection; check. Check, check, check, whatever. This stuff is getting better.

Slowly but surely, F# is inching its way into direct competition with MatLab and Mathematica. But there is one key point here that bears stating and repeating. F# runs compiled code, under all of the traditional conditions of .NET with IL and JIT. This means, just sitting in front of the new fsi, I'll be ahead of the curve on performance. Let me state that again: Using fsi with F# in VS2005 in the new release means that I'll have an environment that meets most criteria for MatLab or Mathematica in core UI features and is compiled.

If you have ever used the big number capabilities in Mathematica, you know that I'm not underestimating the issue when I say that it is slow. The syntax is beautiful and the ability to manipulate stuff in Mathematica is first rate, but arbitrary precision arithmetic is SLOW. In F#, this is not the case. BigNums and BigRationals have found their new place at JJB Research and I've stated that sometime ago (August, 2005, I think). That I now have a comparable interactive view in the new fsi means that I can better interact with my data, my code, my session, etc.

There remains much work ahead here. The mathematics libraries of F# are improving, but are not at the level of maturity that commercial products enjoy. I hope that hubFS initiatives improve this state, at least in community. Additionally, the UI for F# improves as we see here. The manipulation of core mathematics symbols in Mathematica is outstanding. While F# has room to grow, I hope that my second directive (F# and Maths) puts me in a position where I can work on WPF front ends that use the standard (cool) math symbology and actually try to provide further framework for F# interactivity.

From where I sit, those bignums are looking bigger already . . .