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Introduction to coulomb

Quick Start


API documentation for coulomb is hosted at


Include coulomb with your Scala project:

libraryDependencies += "com.manyangled" %% "coulomb-core" % "0.8.0"
libraryDependencies += "com.manyangled" %% "coulomb-units" % "0.8.0"

import statements

Import coulomb definitions:

// fundamental coulomb types and methods
import coulomb.*
import coulomb.syntax.*

// algebraic definitions
import algebra.instances.all.given
import coulomb.ops.algebra.all.given

// unit and value type policies for operations
import coulomb.policy.standard.given
import scala.language.implicitConversions

// unit definitions
import{*, given}


Use coulomb to do typelevel unit analysis in Scala!

// acceleration
val a = 9.8.withUnit[Meter / (Second ^ 2)]
// a: Quantity[Double, /[Meter, ^[Second, 2]]] = 9.8

// time or duration
val t = 10.withUnit[Second]
// t: Quantity[Int, Second] = 10

// velocity
val v = a * t
// v: Quantity[Double, /[Meter, Second]] = 98.0

// position
val x = a * (t.pow[2]) / 2
// x: Quantity[Double, Meter] = 490.00000000000006

Improper unit analysis is a compile-time failure.

val time = 1.withUnit[Second]
val dist = 1.withUnit[Meter]

// Incompatible unit operations are a compile-time type error
val fail = time + dist
// error:
// Addition not defined in scope for Quantity[Int,] and Quantity[Int,].
// I found:
//     coulomb.policy.standard.ctx_add_1V2U[Int,, Int,
//](<:<.refl[Int], scala.util.NotGiven.value,
//       coulomb.policy.standard.ctx_Quantity_Conversion_2V2U[Int,
//, Int,](
//         coulomb.policy.standard.ctx_VC_Int[Int](scala.math.Numeric.IntIsIntegral),
//         /* missing */
//           summon[
//             coulomb.conversion.UnitConversion[Int,,
//     ]
//           ]
//       ),
//     ???)
// But no implicit values were found that match type coulomb.conversion.UnitConversion[Int,,
// val fail = time + dist
//                   ^^^^


coulomb publishes the following packages

name description
coulomb-core Provides core coulomb logic. Defines policies for Int, Long, Float, Double.
coulomb-units Defines common units, including SI, MKSA, Accepted, time, temperature, and US traditional
coulomb-spire Defines policies for working with Spire and Scala numeric types
coulomb-refined Unit analysis with typelevel refined awareness
coulomb-pureconfig Configuration I/O with Quantity values
coulomb-runtime Runtime units and quantities
coulomb-parser Parsing of expressions into runtime units


The following resources expand the concepts behind coulomb and typelevel unit analysis:

Previous versions

Versions of coulomb beginning with 0.6 require Scala 3, and are not compatible with Scala 2.13.

coulomb versions <= 0.5.x require Scala 2.13. The 0.5.x series will continue to be supported on a maintenance basis only.

You can browse the legacy scala doc for the *_2.13 packages here.

The legacy tutorial documentation will continue to be viewable here.

The scala2 branch of coulomb on github will continue to hold coulomb <= 0.5.x

Code of Conduct

The coulomb project supports the Scala Code of Conduct. All contributors are expected to respect this code. Any violations of this code of conduct should be reported to the author.