This library provides generic derivation of dhallj Encoder and Decoder typeclasses using magnolia.
To use dhallj-magnolia add the following dependency to your build.sbt:
libraryDependencies += "pl.msitko" %% "dhallj-magnolia" % "0.1.3"
Dhallj-magnolia is published for both Scala 2.13 and Scala 3. Limitations of Scala 3 branch of the library:
- Your project consuming dhallj-magnolia has to have the compilation flag
-Yretain-treesenabled if you rely on default values for case classes - Derivation doesn't work for value classes
Consider the following ADT:
sealed trait Bar
final case class Bar1(a: Int) extends Bar
final case class Bar2(b: String) extends Bar
final case class Foo(a: Int, b: String, bar: Bar)import org.dhallj.codec.syntax._
import pl.msitko.dhallj.generic.encoder.auto._
val input = Foo(12, "abc", Bar2("abcd"))
input.asExpr.toString
// """{a = 12, b = "abc", bar = (<Bar1 : {a : Natural} | Bar2 : {b : Text}>.Bar2) {b = "abcd"}}"""Additionally, dhallj's Encoder[A] has dhallType method which prints out dhall type for A. So, following the example, we can:
import org.dhallj.codec.Encoder
println(Encoder[Foo].dhallType(None, None))
// {a : Natural, b : Text, bar : <Bar1 : {a : Natural} | Bar2 : {b : Text}>}import org.dhallj.syntax._
import pl.msitko.dhallj.generic.decoder.auto._
val input = """{a = 12, b = "abc", bar = (<Bar1 : {a : Natural} | Bar2 : {b : Text}>.Bar2) {b = "abcd"}}"""
for {
parsed <- input.parseExpr
decoded <- parsed.normalize().as[Foo]
} yield decoded
// Right(Foo(12,abc,Bar2(abcd)))import org.dhallj.codec.syntax._
import pl.msitko.dhallj.generic.encoder.semiauto._
implicit val barEncoder = deriveEncoder[Bar]
implicit val fooEncoder = deriveEncoder[Foo]
val input = Foo(12, "abc", Bar2("abcd"))
input.asExpr.toString
// """{a = 12, b = "abc", bar = (<Bar1 : {a : Natural} | Bar2 : {b : Text}>.Bar2) {b = "abcd"}}"""import org.dhallj.syntax._
import pl.msitko.dhallj.generic.decoder.semiauto._
implicit val barDecoder = deriveDecoder[Bar]
implicit val fooDecoder = deriveDecoder[Foo]
val input = """{a = 12, b = "abc", bar = (<Bar1 : {a : Natural} | Bar2 : {b : Text}>.Bar2) {b = "abcd"}}"""
for {
parsed <- input.parseExpr
decoded <- parsed.normalize().as[Foo]
} yield decoded
// Right(Foo(12,abc,Bar2(abcd)))
