systemfw / eidos

A tiny and principled library for type-safe IDs

Version Matrix


Eidos is a tiny and principled library for modelling IDs. It does one thing and does it well, allowing you to build tagged IDs with à la carte pretty-printing and validation, and an emphasis on type safety and correct-by-construction code. We can do better than String.

import eidos._

case object QnD
type QnD = QnD.type

case object Customer extends MakeLabel with UUID
type Customer = Customer.type

case object Device extends CustomLabel with Regex {
 def pattern = "(abc)+12"
 def label = "Phone"
type Device = Device.type

// and then

scala > Id.of[QnD]("no validation required!")
res1: Id[QnD] = Id(no validation required!)

scala> Id.of[Customer]("e07fa50f-7ddf-4e7c-acf5-420406e5a7c5")
res2: Option[Id[Customer]] = Some(CustomerId(e07fa50f-7ddf-4e7c-acf5-420406e5a7c5))

scala> Id.of[Customer]("not-a-uuid")
res3: Option[Id[Customer]] = None

scala> Id.of[Device]("abcabc12")
res4: Option[Id[Device]] = Some(PhoneId(abcabc12))

Getting Eidos

Add the following to your build.sbt. Builds are available for scala 2.11.x and 2.12.x

libraryDependencies += "org.systemfw" %% "eidos" % "0.1.1"


Have a look at the User Guide for detailed documentation