Iron is a lightweight library for refined types in Scala 3.
It enables attaching constraints/assertions to types, to enforce properties and forbid invalid values.
- Catch bugs. In the spirit of static typing, use more specific types to avoid invalid values.
- Compile-time and runtime. Evaluate constraints at compile time, or explicitly check them at runtime (e.g. for a form).
- Seamless. Iron types are subtypes of their unrefined versions, meaning you can easily add or remove them.
- No black magic. Use Scala 3's powerful inline, types and restricted macros for consistent behaviour and rules. No unexpected behaviour.
- Extendable. Easily create your own constraints or integrations using classic typeclasses.
To learn more about Iron, see the microsite.
def log(x: Double :| Greater[0.0]): Double =
Math.log(x) //Used like a normal `Double`
log(1.0) //Automatically verified at compile time.
log(-1.0) //Error: -1.0 is not greater than 0.0!
val runtimeValue = ???
log(runtimeValue.refine) //Explicitly refine your external values at runtime.
runtimeValue.refineEither.map(log) //Use monadic style for functional validation
runtimeValue.refineEither[Greater[0.0]].map(log) //More explicitlySBT:
libraryDependencies += "io.github.iltotore" %% "iron" % "version"Mill:
ivy"io.github.iltotore::iron:version"Note: replace version with the version of Iron.
| Module | JVM | JS | Native |
|---|---|---|---|
| iron | ✔️ | ✔️ | ✔️ |
| iron-cats | ✔️ | ✔️ | ✔️ |
| iron-circe | ✔️ | ✔️ | ✔️ |
| iron-zio-json | ✔️ | ✔️ | ❌ |