Are units of measurement unique to F#?

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+6 Q:

Are units of measurement unique to F#?

I was reading Andrew Kennedy's blog post series on units of measurement in F# and it makes a lot of sense in a lot of cases. Are there any other languages that have such a system?

Edit: To be more clear, I mean the flexible units of measurement system where you can define your own arbitrarily.

+1 A:

I'm not sure if this really counts, but the RPL system on my HP-48 calculator does have similar features. I can write 40_gal 5_l + and get the right answer of 156.416 liters.

Pi 2008-09-20 05:34:07

I was referring to the system by which you can define arbitrary units of measurement, but that's interesting nonetheless.

Cody Brocious 2008-09-20 05:35:36

I don't have my manual for my '48 handy, but I believe it lets you do this as well.

Pi 2008-09-20 05:38:00

+3 A:

I believe I saw that Fortress support this, I'll see if I can find a link.

I can't find a specific link, but the language specification makes mention of it in a couple of places. The 1.0 language specification also says that dimensions and units were temporarily dropped from the specification (along with a whole heap of other features) to match up with the current implementation. It's a work in progress, so I guess things are in flux.

Greg Hewgill 2008-09-20 05:35:57

I'm pretty sure Ada has it.

TraumaPony 2008-09-20 05:36:09

I don't think Ada has this feature directly, but you can certainly declare types that are based on another type (ie. integer or float) but are incompatible types as far as the compiler is concerned. So you couldn't directly add metres and feet without converting one of them.

Greg Hewgill 2008-09-20 05:45:27

There is a library for it: "Units of measurement for Ada", http://www.dmitry-kazakov.de/ada/units.htm

Peter Mortensen 2009-08-21 14:47:34

+6 A:

Does TI-89 BASIC count? Enter 54_kg * (_c^2) (or something like that) and it will give you an answer in kilograms.

Other than that, I can't recall any languages that have it built in, but any language with decent OO should make it simple to roll your own. Which means someone else probably already did.

Google confirms. For example, here's one in Python. __repr__ could easily be amended to also select the most appropriate derived unit, etc.

CPAN has several modules for Perl: Physics::Unit, Data::Dimensions, Class::Measure, Math::Units::PhysicalValue, and a handful of others that will convert but don't really combine values with units.

Eevee 2008-09-20 05:45:34

+1 A:

F# is the first mainstream language to support this feature.

Jon Harrop 2008-10-19 02:29:01

+1 A:

There is also a Java specification for units at http://jcp.org/en/jsr/detail?id=275 and you can already use it from here http://jscience.org/

Lukasz 2008-11-17 00:13:56

+4 A:

Nemerle had compiler-checked Units of Measure in 2006.

http://nemerle.org

http://nemerle.org/forum.old/viewtopic.php?t=265&view=previous&sid=00f48f33fafd3d49cc6a92350b77d554

Kirill Osenkov 2008-11-17 00:17:21

I'm sure you'd be able to do this with most dynamic languages (javascript, python, ruby) by carefully monkey-patching some of the base-classes. You might get into problems though when working with imperial measurements.

digitala 2008-11-17 00:27:02

+2 A:

C++ has it, in the form of boost::units.

puetzk 2008-11-17 01:13:25

well I made QuantitySystem library especially for units in C#, however its not compile time checking

but I've tried to make it run as I wanted

also it supports expansion so you can define your unique units

http://QuantitySystem.CodePlex.com

also it can differentiate between Torque and Work :) [This was important for me]

the library approach is from Dimension to units all I've seen till now units only approach.

2009-06-14 23:02:27

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Are units of measurement unique to F#?

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