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

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Friday, May 09, 2003

Straightjackets

Phil Windley on dynamic typing...

A strongly typed language merely creates an environment so that the type-checker can automatically check the type constraints for you at the cost of restricting some genuinely useful things you might want to do.

One thing you want to do that is easier with dynamically type checking is testing. Only time spent developing significant systems in dynamic languages will bear this out. Illustrations don't capture the reality.

People see that static types can catch things early. They don't see that those things aren't important since they get caught early in dynamic tests anyway. Yes, you have to write good tests. Can anyone tell me when that's not the case?

Neither is it apparent on paper that refactoring large systems, or just experimenting with large systems, goes much more quickly when you have to change less code to get a small test to run. You trust that the complete set of tests will catch everything else when the experiment is ready to be integrated back into a complete working system.

But during spike experiments you want to ignore the irrelevent, create mock objects, even entire "mock databases", and play what if on isolated bits of code, even within large currently running systems. Doesn't happen easily in Java-like languages. Compilers that have no clue of what you really care about in the moment. They make you dot that 'i' over there and cross this 't' over here before you can even get to the bits of interest.

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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.