On Fri, 25 Sep 2009 13:44:00 +0900 "Stephen J. Turnbull" <stephen@xemacs.org> wrote:
Mike Meyer writes:
On Thu, 24 Sep 2009 20:06:22 -0400 Gerald Britton <gerald.britton@gmail.com> wrote:
I think that the idea that there is a continuum from weak typing to strong typing is useful.
I think it's fundamentally broken, at least as badly as the notion of a political spectrum from liberal to conservative. The problem with both of those is that there's more than one axis involved.
The notion that you can't order multidimensional sets (where each dimension is ordered) is simply wrong. You do it every day when you decide to have "a Big Mac with coffee" instead of "a QuarterPounder with a vanilla shake".
The idea that ordering multidimensional sets matters is simply wrong. Obviously, you can impose an order - and probably many - on any countable set - or any space with a countable number of axis. That leaves three problems, in increasing order of pain: 1) It's not clear the resulting object can be described as a continuum. 2) It's not clear that any of the orders are meaningful. 3) Unless everyone agrees on the order, it's still useless. #3 is the critical one. You've basically moved the problem from selecting one from a set of axis to selecting one from a set of possible orders of a set of axis. Which starts with selecting the set of meaningful axis from the power set - which is noticeably larger than set of axis. The number of meaningful orderings may well approach the power set in size.
The question here then is simply "what is the quality of the approximation, and are there structural shifts to account for?"
*After* you've agreed on which axis matter, and that the PCA is the ordering you want to use.
Just as people can have a liberal position on one issue while having a conservative position on another, languages can have some features that give them "weak typing" and others that give them "strong typing".
They can take such positions, but historically the correlations were generally high. What has happened in politics in many countries is that there has been a structural realignment such that the component axis traditionally labeled "liberal to conservative" is no longer so much stronger than other components of variation. That doesn't mean that the traditional axis was never useful, nor that a new principal axis hasn't been established (although I don't think it has been established yet in American politics).
I've seen people using two political axis for the last couple of decades: financially conservative/liberal and personally conservative/liberal. You can of course collapse that to one axis. You can also describe the solar system with epicycles. But using two axes - or ellipses - is a more powerful model to work with. Which is the point - until we can agree
Axis so far: declarations: yes/no/optional. Variables have types: (yes/no/optional). Implicit conversion: yes/no, with a different answer possible for every operand and tuple of operators types in the language.
My personal resolution of strong vs. weak typing is that it's useful to help explain which languages I like (strongly typed ones) vs. those I don't.
This, of course, tells me pretty nearly *nothing* about which languages you like.
In this, only the implicit conversion axis matters much.
I suspect you care about more than that - or do you weigh Python converting everything to a bool in a boolean context as equivalent to some language that will convert everything to a string if there's a string in the expression? <mike -- Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html Independent Network/Unix/Perforce consultant, email for more information. O< ascii ribbon campaign - stop html mail - www.asciiribbon.org