"I have a mind like a steel... uh... thingy." Patrick Logan's weblog.

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Friday, May 12, 2006

Virtual Machines for Small Form Factors?

Tim O'Reilly writes about the value of small form factor devices connected to Internet data...

It's a sign that special purpose hardware providing access to internet data services may eventually be commonplace.
On the other hand I don't want to carry around five or ten devices. I'd rather have a three form factors and carry around one of them, the one that is most useful for the moment. That may be a wrist watch sized device, a larger cell phone sized device, or a small laptop sized device.

I'd like virtual machines running on each of these with images of the systems I want to use. Most of my systems would run on any of the form factors and use as much of the capabilities of each as possible. Everything would be synched, backed up, and enhanced through the Internet to my big system that stays put at home and/or at some other site.

People with ideas for new capabilities would not design new hardware, just new virtual images for the common hardware. Every year or so I would upgrade one or more of the devices to the newest physical devices available. All the old images would continue to run.

Thursday, May 11, 2006

Expressionism

Update: Don sets me straight, and rightfully so with a good exposition. I did not do my homework.

End Update

Don Box writes about compiling code on the fly in C# 3.0, kind of, I think...

Expression<Func<int, int>> expr = a => a + 3;
Console.WriteLine(expr); // prints "a => Add(a, 3)"
Func<int, int> func = expr.Compile(); // LCG's an MSIL method from the expr
Console.WriteLine(func(4)); // prints "7"
He equates (incorrectly from what I can tell) the above C# 3.0 with the following Scheme from 25 years ago...
(define expr '(lambda (a) (+ a 3)))
(display expr)
(define func (eval expr (scheme-report-environment 5)))
(display (func 4))
I think the comparison has some flaws. Maybe I just don't know enough about C# 3.0 (until just now I knew nothing about it).

First of all the expression (quote (lambda (a) (+ a 3))) is *data*, in particular a list of atoms and nested lists of atoms. That list is bound to a variable called expr, whose name is conveying that the data *may* be evaluated as a lambda expression. But it is not a lambda expression, it is a list. The C# code appears to require something to be declared as an Expression. Is such a class something that can be built programmatically? Or does it have to be declared and constructed intact?

Plus if it is already an expression, why would it need to be compiled? In the Scheme example, the list has to be evaluated to get a lambda, i.e. the function that the original list of atoms resembles. If you start with an expression, you should not have to do an eval or compile to get an evaluatable thing. That's just wrong. You'd just do this...

(define func (lambda (a) (+ a 3)))  ; No QUOTE form. It's already a function.
(display (func 4))                  ; Just apply it.

Or even more simply...

(display ((lambda (a) (+ a 3)) 4))  ; No QUOTE form. Just apply it.

One more thing: where is the QUOTE form in the C# code? The quote mark in Scheme is short hand for wrapping a special form (QUOTE ...) around something that you consider "data". i.e. QUOTE prevents evaluation. Does the Expression class automatically get recognized by the C# evaluator to prevent the RHS from being evaluated? Come on, either the RHS is data or the RHS is an expression. Or can the compiler only work with a special kind of data that happens to be called an Expression. Weird any way you slice it from what I can make of it.

I don't get it, and maybe there is a more complete and logical explanation. Maybe the answer is "Pat, you're confused because you already know a simpler language like Scheme." Yeah, so why not use C++?

As it stands it looks like there is a bit of confusion and complication that separates C# 3.0 from simpler, more agile languages like Scheme, Python, and Ruby.

Just use those languages, folks. Don't get strung out on these incremental "improvements" to a language that was too complex to begin with.

Wednesday, May 10, 2006

Sunday, May 07, 2006

Tell All The People - Follow Me Down

A musical tribute to Stephen Colbert...

There's no denying the huge supporting role Jon Stewart played in this victory. Both Stewart and Colbert had to use their people-skills over a long period of time to gain access to their marks. Jon Stewart loaded the bases and Colbert hit it over the fence. It reminds me a bit of the tactics of the "Yes Men".

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About Me

Portland, Oregon, United States
I'm usually writing from my favorite location on the planet, the pacific northwest of the u.s. I write for myself only and unless otherwise specified my posts here should not be taken as representing an official position of my employer. Contact me at my gee mail account, username patrickdlogan.