martintrojer/frins

A practical unit-of-measure calculator DSL for Scala

Frins

Frins is a practical unit-of-measure calculator DSL for Scala.

Key features;

• Tracks units of measure through all calculations allowing you to mix units of measure transparently
• Comes with a huge database of units and conversion factors
• Inspired by the Frink project and Frinj
• Tries to combine Frink's fluent calculation style with idiomatic Scala

Artifacts

Add the following lines to your build.sbt

resolvers += "Sonatype snapshots" at "http://oss.sonatype.org/content/repositories/snapshots/"

libraryDependencies += "io.github.martintrojer" % "frins_2.10" % "0.1-SNAPSHOT"

Usage

Turn your sbt console into an (even more) powerful calculator;

$ sbt console
scala> import frins._
scala> initDatabases

You are now ready to go! Frins keeps it's values in instances of the Number class, which contains a Double value and a Map of Units. Once you have a Number object you can use it in calculations as you would normally use Doubles.

There are convenience Frins Number builders using the form N(value, 'unit, 'unit, ...) (value can be omitted) and implicits conversions from other number types and scala symbols (denoting the unit) to Frins Numbers.

scala> 'teaspoon * 'water * ('c ** 2)
res0: frins.Number[Double] = 4.429893807970541E14 m^2 kg s^-2 [energy]

That's the energy contained in one teaspoon of water (using E=mc^2). Wow, big number, how much is that "in real money"?

scala> res0 to 'gallons * 'gasoline
res1: frins.NumberT = 3164209.8628361006  [dimensionless]

There you have it, the energy in one teaspoon of water (according to Einstein) is equivalent to burning 3 million (!) gallons of gasoline.

For more examples and explanations of the Number builders (and more!) see the example calculations below.

Examples

• See example calculations for ideas (and some laughs)...

• Video of a Frinj talk (Frinj is Frins' sibling project)

Finally, check the wiki for more information.

License

Copyright (C) 2013 Martin Trojer

Distributed under the Eclipse Public License.