Stephen Pope was able to build a really nice "units" system
using normal Smalltalk syntax. He did it in the context of a
music system where you could say things like:

  sound pitch: 440 asHz

or

  sound pitch: 69 asMidiKey

The selectors "asHz" and "asMidiKey" are unary messages that
return a pitch object, I believe. (Stephen: please correct me if
I'm not explaining this correctly.)

	-- John