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Implicitly abstract numerics for Scala. Enables a single math expression to apply across number types.
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README.md

NumVal — Implicitly abstract numerics

The NumVal Scala trait enables developers to write a math expression once, then implicitly apply it to any of the 10 built-in number types. Like AnyVal, NumVal acts as a common super-type of the primitive types: Boolean, Byte, Char, Short, Int, Long, Float and Double, but also includes Scala's BigInt and BigDecimal types. Unlike AnyVal, NumVal supplies common arithmetic operations and most of the operations found in scala.math. Besides applying to any number type, NumVal operations also fix a number of anomalous behaviors in the standard math library, described in the documentation.

NumVal was developed to satisfy these goals:

  • Transparent (implicit) abstraction across all Scala number types
  • Arbitrary precision, using BigInt and BigDecimal types
  • Accuracy to the last (rounded) digit
  • Mathematical correctness for all input values
  • Performance

Trait NumVal was initially developed to support a Java-based graphics animation library, Formulo, that is not yet released. I decided to publish NumVal as a separate project, since generalized numerics has broader utility than merely for graphical applications.

Installation

NumVal is hosted on Maven Central. You can add it as a dependency to your build.sbt file. It is built for Scala 2.9.1, 2.9.2, 2.9.3-RC, and dash-numbered variants.

libraryDependencies += "org.oxland" %% "numval" % "0.1.0"

Usage

Include one or both of these imports in your source code:

  • import org.oxland.math._ // to explicitly define NumVal variables
  • import org.oxland.math.NumVal._ // to implicitly convert among number types

The first import, ~.math._, lets you explicitly reference the NumVal trait, for example:

  • import org.oxland.math._
  • def add(a:NumVal, b:NumVal):NumVal = a + b

The second import, ~.NumVal._, enables implicit conversions from any of the 10 Scala number types to NumVal, as needed to invoke a NumVal operation.

For example:

  • import org.oxland.math.NumVal._
  • true * math.Pi // since the Boolean type "true" has no '*' operator, it is implicitly wrapped as a NumVal

In Scala you can restrict the scope of either import by placing it in the curly brackets of a block. Either import can be used independently of the other.

Documentation

Build yourself

$ cd NumVal
$ ./sbt
> compile

Contact

Robert Kohlenberger (kohlenrw@bdumail.com)

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