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Re: dynamic vs. static typing

On Nov 24, 2003, at 10:09 PM, Matt Hellige wrote:
> There's one other interesting and important aspect: a well-designed
> static type system provides a second perspective that is provably
> complete in some relevant and well-specified way, as opposed to, for
> example, unit tests. With unit tests, the responsibility for ensuring
> (and understanding) completeness of coverage lies entirely with the
> programmer.

That's true, but only the programmer knows what the program is supposed 
to do. A missile guidance program can pass a static type check and 
still not guide the missile to the correct location. Of the almost 
limitless number of possible bugs, type checking (assuming few dynamic 
operations are done) eliminates, at best, a extremely small percentage. 
And that percentage is most likely a tiny subset of the very large 
percentage that testing eliminates.

-- Steve