Ammonite classpath clashes with Github4s (java.lang.AbstractMethodError) - ammonite

Question

I’m writing an ammonite script to work with Github4s library to access the github api and have a issue, probably with the classpath. The simple version of the script is as follows:
import $ivy.`com.47deg::github4s:0.17.0`, github4s.Github, github4s.Github._, github4s.jvm.Implicits._, scalaj.http.HttpResponse
val listCommits = Github().repos.listCommits("lihaoyi", "ammonite")
listCommits.exec[cats.Id, HttpResponse[String]]() match {
case Left(e) => println(s"Something went wrong: ${e.getMessage}")
case Right(r) => r.result.foreach { commit => println(s"${commit.sha}:
${commit.message.take(35)}") }
}
It's pretty much copied from the github4s tutorial and it fails with:
java.lang.AbstractMethodError
jawn.CharBasedParser.parseString(CharBasedParser.scala:90)
jawn.CharBasedParser.parseString$(CharBasedParser.scala:87)
jawn.StringParser.parseString(StringParser.scala:15)
jawn.Parser.rparse(Parser.scala:428)
jawn.Parser.parse(Parser.scala:337)
jawn.SyncParser.parse(SyncParser.scala:24)
jawn.SupportParser.$anonfun$parseFromString$1(SupportParser.scala:15)
jawn.SupportParser.parseFromString(SupportParser.scala:15)
jawn.SupportParser.parseFromString$(SupportParser.scala:14)
io.circe.jawn.CirceSupportParser$.parseFromString(CirceSupportParser.scala:7)
io.circe.jawn.JawnParser.parse(JawnParser.scala:16)
io.circe.parser.package$.parse(package.scala:8)
io.circe.Parser.decode(Parser.scala:26)
io.circe.Parser.decode$(Parser.scala:25)
io.circe.parser.package$.decode(package.scala:5)
github4s.HttpRequestBuilderExtensionJVM.decodeEntity(HttpRequestBuilderExtensionJVM.scala:89)
github4s.HttpRequestBuilderExtensionJVM.decodeEntity$(HttpRequestBuilderExtensionJVM.scala:88)
github4s.jvm.Implicits$.decodeEntity(Implicits.scala:21)
Exactly the the same code works in a simple SBT project that makes me think Ammonite injects something in the classpath and it breaks github4s.
Is there a way to have a cleaner classpath in ammonite scripts or how else can I go around this issue?

Answer 1

I had the same problem as you. Here, what I figured:
Ammonite 1.0.3 does indeed use (indirectly) jaws 0.10.4 (by upickle). However, unstable version of Ammonite is already migrated to newer version of upickle, with in turns use jaws 0.11.
So with Ammonite unstable I was able to run my problem without running into AbstractMethodError issue.