Units of Measure in F#: Part One, Introducing Units

http://blogs.msdn.com/b/andrewkennedy/archive/2008/08/29/units-of-measure-in-f-part-one-introducing-units.aspx

by strlen • 16 years ago

4 1 16 years ago

blogs.msdn.com

equark• 16 years ago

Units of measure has always struck me as a pet feature of F# that's only there because it happened to be what somebody's PhD dissertation was written on. Whether it is useful in practice is unclear.

I saw Don Syme give a presentation where he tried to add twice the variance to the mean of a variable. This is actually perfectly sensible to do -- it's some quantile point. But it gives a type error since variance has units squared in it. So he took the square root to solve the "problem." Obviously it was just a demo, but he claimed the the Microsoft Ad team had similar bugs confusing the variance and standard deviation. I can almost imagine some code maintenance guy adding units of measure and thinking there's a bug in some carefully constructed algorithm when in fact there is not.

All sorts of statistics have this issue.

Units of Measure in F#: Part One, Introducing Units

Related Stories