I'm trying to create a extremely simple Telegram bot in Scala using bot4s. I'm pretty much following the example there. Here's the code:
package info.jjmerelo.BoBot
import cats.instances.future._
import cats.syntax.functor._
import com.bot4s.telegram.api.RequestHandler
import com.bot4s.telegram.api.declarative.Commands
import com.bot4s.telegram.clients.{FutureSttpClient, ScalajHttpClient}
import com.bot4s.telegram.future.{Polling, TelegramBot}
import scala.util.Try
import scala.concurrent.Future
import com.typesafe.scalalogging.Logger
object BoBot extends TelegramBot
with Polling
with Commands[Future] {
implicit val backend = SttpBackends.default
def token = sys.env("BOBOT_TOKEN")
override val client: RequestHandler[Future] = new FutureSttpClient(token)
val log = Logger("BoBot")
// val lines = scala.io.Source.fromFile("hitos.json").mkString
// val hitos = JSON.parseFull( lines )
// val solo_hitos = hitos.getOrElse( hitos )
onCommand("hey") { implicit msg =>
log.info("Hello")
reply("Conseguí que funcionara").void
}
}
And here's the build.sbt
name := "bobot"
version := "0.0.1"
organization := "info.jjmerelo"
libraryDependencies += "com.bot4s" %% "telegram-core" % "4.4.0-RC2"
val circeVersion = "0.12.3"
libraryDependencies ++= Seq(
"io.circe" %% "circe-core",
"io.circe" %% "circe-generic",
"io.circe" %% "circe-parser"
).map(_ % circeVersion)
libraryDependencies += "com.typesafe.scala-logging" %% "scala-logging" % "3.9.2"
retrieveManaged := true
Circe is for later
Anyway, I managed to compile most of it, but I still get these two errors:
[info] compiling 2 Scala sources to /home/jmerelo/Asignaturas/cloud-computing/BoBot/target/scala-2.12/classes ...
[error] /home/jmerelo/Asignaturas/cloud-computing/BoBot/src/main/scala/info/jjmerelo/BoBot.scala:21:26: not found: value SttpBackends
[error] implicit val backend = SttpBackends.default
[error] ^
[error] /home/jmerelo/Asignaturas/cloud-computing/BoBot/src/main/scala/info/jjmerelo/BoBot.scala:23:49: could not find implicit value for parameter backend: com.softwaremill.sttp.SttpBackend[scala.concurrent.Future,Nothing]
[error] Error occurred in an application involving default arguments.
[error] override val client: RequestHandler[Future] = new FutureSttpClient(token)
[error] ^
[error] two errors found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 5 s, completed 11 nov. 2020 8:19:38
I can't figure out either of the two. SttpBackends is missing, that's clear, but there's nothing in the example that indicates it's needed, or, for that matter, what library should be included. The second one about the default arguments I simply can't figure it out, even if I define token as String or if I change def to val. Any idea?
Your error messages is associated with each other.
First error tells us that compiler couldn't find object SttpBackends which has field of SttpBackend.
The second one tells us that compiler couldn't find implicit backend: SttpBackend for constructing FutureSttpClient. It requires two implicits: SttpBackend and ExecutionContext.
class FutureSttpClient(token : _root_.scala.Predef.String,
telegramHost : _root_.scala.Predef.String = { /* compiled code */ })
(implicit backend : com.softwaremill.sttp.SttpBackend[scala.concurrent.Future, scala.Nothing],
ec : scala.concurrent.ExecutionContext)
extends com.bot4s.telegram.clients.SttpClient[scala.concurrent.Future] {...}
You can create it by yourself as in bot4s examples.
If you will try to find SttpBackends object in bot4s library you would found this code in bot4s examples:
import com.softwaremill.sttp.okhttp._
object SttpBackends {
val default: SttpBackend[Future, Nothing] = OkHttpFutureBackend()
}
add this object to your project to make it compilable.
I am trying to comile and run simple h2o scala code. But when I do sbt package I get errors.
Am I missing something in the sbt file
This is my h2o scala code
import org.apache.spark.SparkContext
import org.apache.spark.SparkContext._
import org.apache.spark.SparkConf
import org.apache.spark.sql._
import ai.h2o.automl.AutoML
import ai.h2o.automl.AutoMLBuildSpec
import org.apache.spark.h2o._
object H2oScalaEg1 {
def main(args: Array[String]): Unit = {
val sparkConf1 = new SparkConf().setMaster("local[2]").setAppName("H2oScalaEg1App")
val sparkSession1 = SparkSession.builder.config(conf = sparkConf1).getOrCreate()
val h2oContext = H2OContext.getOrCreate(sparkSession1.sparkContext)
import h2oContext._
import java.io.File
import h2oContext.implicits._
import water.Key
}
}
And this is my sbt file.
name := "H2oScalaEg1Name"
version := "1.0"
scalaVersion := "2.11.12"
scalaSource in Compile := baseDirectory.value / ""
libraryDependencies += "org.apache.spark" %% "spark-core" % "2.2.3"
libraryDependencies += "org.apache.spark" %% "spark-sql" % "2.2.0"
libraryDependencies += "org.apache.spark" %% "spark-hive" % "2.2.0"
libraryDependencies += "ai.h2o" % "h2o-core" % "3.22.1.3" % "runtime" pomOnly()
When I do sbt package I get these errors
[error] /home/myuser1/h2oScalaEg1/H2oScalaEg1.scala:7:8: not found: object ai
[error] import ai.h2o.automl.AutoML
[error] ^
[error] /home/myuser1/h2oScalaEg1/H2oScalaEg1.scala:8:8: not found: object ai
[error] import ai.h2o.automl.AutoMLBuildSpec
[error] ^
[error] /home/myuser1/h2oScalaEg1/H2oScalaEg1.scala:10:25: object h2o is not a member of package org.apache.spark
[error] import org.apache.spark.h2o._
[error] ^
[error] /home/myuser1/h2oScalaEg1/H2oScalaEg1.scala:20:20: not found: value H2OContext
[error] val h2oContext = H2OContext.getOrCreate(sparkSession1.sparkContext)
[error] ^
[error] /home/myuser1/h2oScalaEg1/H2oScalaEg1.scala:28:10: not found: value water
[error] import water.Key
[error] ^
[error] 5 errors found
How can I fix this problem.
My spark version in spark-2.2.3-bin-hadoop2.7
Thanks,
marrel
pomOnly() in build.sbt indicates to the dependency management handlers that jar libs/artifacts for this dependency should not be loaded and to only look for the metadata.
Try to use libraryDependencies += "ai.h2o" % "h2o-core" % "3.22.1.3" instead.
Edit 1: Additionally I think you are missing (at least) one library dependency:
libraryDependencies += "ai.h2o" % "h2o-automl" % "3.22.1.3"
see: https://search.maven.org/artifact/ai.h2o/h2o-automl/3.22.1.5/pom
Edit 2:
The last dependency you are missing is sparkling-water-core:
libraryDependencies += "ai.h2o" % "sparkling-water-core_2.11" % "2.4.6" should do the trick.
Here is the github of sparkling-water/core/src/main/scala/org/apache/spark/h2o
.
I'm trying to create Show Instance for my custom Config class.
The build.sbt file is -
name := "circe-demo"
version := "0.1"
scalaVersion := "2.11.12"
resolvers += Resolver.bintrayRepo("ovotech", "maven")
libraryDependencies += "io.circe" %% "circe-core" % "0.11.0"
libraryDependencies += "io.circe" %% "circe-parser" % "0.11.0"
libraryDependencies += "io.circe" %% "circe-generic" % "0.11.0"
libraryDependencies += "org.typelevel" %% "kittens" % "1.2.0"
libraryDependencies ++= Seq(
"is.cir" %% "ciris-cats",
"is.cir" %% "ciris-cats-effect",
"is.cir" %% "ciris-core",
"is.cir" %% "ciris-enumeratum",
"is.cir" %% "ciris-refined"
).map(_ % "0.12.1")
Complete code is -
import enumeratum.{Enum, EnumEntry}
sealed abstract class AppEnvironment extends EnumEntry
object AppEnvironment extends Enum[AppEnvironment] {
case object Local extends AppEnvironment
case object Testing extends AppEnvironment
case object Production extends AppEnvironment
override val values: Vector[AppEnvironment] =
findValues.toVector
}
import java.net.InetAddress
import scala.concurrent.duration.Duration
final case class ApiConfig(host: InetAddress, port: Int, apiKey: String, timeout: Duration)
import java.net.InetAddress
import cats.Show
import cats.derived.semi
import ciris.config.loader.AppEnvironment.{Local, Production, Testing}
import enumeratum.EnumEntry
import eu.timepit.refined.auto._
import eu.timepit.refined.types.string.NonEmptyString
import scala.concurrent.duration._
final case class Config(appName: NonEmptyString, environment: AppEnvironment, api: ApiConfig)
object Config {
implicit val showConfig: Show[Config] = {
implicit val showDuration: Show[Duration] =
Show.fromToString
implicit val showInetAddress: Show[InetAddress] =
Show.fromToString
implicit def showEnumEntry[E <: EnumEntry]: Show[E] =
Show.show(_.entryName)
// Show.show[Config](x => s"api = ${x.api} appName = ${x.appName} environment ${x.environment}")
semi.show
}
}
semi.show in the above code throws the below exception -
[error] /Users/rajkumar.natarajan/Documents/Coding/kafka_demo/circe-demo/src/main/scala/ciris/config/loader/Config.scala:32:5: ambiguous implicit values:
[error] both value emptyProductDerivedShow in trait MkShowDerivation of type => cats.derived.MkShow[shapeless.HNil]
[error] and method emptyCoproductDerivedShow in trait MkShowDerivation of type => cats.derived.MkShow[shapeless.CNil]
[error] match expected type cats.derived.MkShow[A]
[error] show
[error] ^
[error] one error found
[error] (Compile / compileIncremental) Compilation failed
[error]
I'm new to functional programming using cats.
How can I resolve this exception.
Unfortunately error reporting when such complicated implicits and macros are involved is far from perfect. The message you see actually means that some required implicits for the real generator (MkShow.genericDerivedShowProduct in this case) have not been found and the search went back to some where basic stuff where there is an ambiguity. And the stuff that is missing is mostly very basic such as an implicit for Show[Int] or Show[String]. The simplest way to get them all is to import cats.implicits._ but that will also bring catsStdShowForDuration which is a Show[Duration]. But since it's implementation is really the same as your custom one, it is easier to remove your custom one. One more thing that is missing is Show[NonEmptyString] and it is easy to create one
implicit def showNonEmptyString: Show[NonEmptyString] = Show.show(nes => nes)
To sum up, when I define your showConfig as
implicit val showConfig: Show[Config] = {
import cats.implicits._
// is already defined in cats.implicits._
//implicit val showDuration: Show[Duration] = Show.fromToString
implicit val showInetAddress: Show[InetAddress] = Show.fromToString
implicit def showEnumEntry[E <: EnumEntry]: Show[E] = Show.show(_.entryName)
implicit def showNonEmptyString: Show[NonEmptyString] = Show.show(nes => nes)
// Show.show[Config](x => s"api = ${x.api} appName = ${x.appName} environment ${x.environment}")
semi.show
}
it compiles for me.
P.S. is there any good reason why you put your AppEnvironment under ciris.* package? I'd say that generally putting your custom code into packages of 3-rd party library is an easy way to mess things up.
I'm trying to use scala-pickling because at site github it seems so easy and clean. But, I'm failing in use it in this simple REPL:
scala> import scala.pickling._
import scala.pickling._
scala> import scala.pickling.Defaults._
import scala.pickling.Defaults._
scala> import binary._
import binary._
scala> class Xpto { var a = 0D; var b = 0 }
defined class Xpto
scala> val v = new Xpto { a = 1.23; b = 5 }
v: Xpto = $anon$1#636d2b03
scala> v.pickle
<console>:19: error: type mismatch;
found : v.type (with underlying type Xpto)
required: ?{def pickle: ?}
Note that implicit conversions are not applicable because they are ambiguous:
both method PickleOps in package pickling of type [T](picklee: T)pickling.PickleOps[T]
and method pickleOps in trait Ops of type [T](picklee: T)scala.pickling.PickleOps[T]
are possible conversion functions from v.type to ?{def pickle: ?}
v.pickle
^
<console>:19: error: value pickle is not a member of Xpto
v.pickle
^
What is wrong?
I did access other issues on StackOverflow with this same type of question, for example:
Scala pickling: Simple custom pickler for my own class?
Obs.: I'm using this reference in build.sbt:
"org.scala-lang.modules" %% "scala-pickling" % "0.10.1"
Are you sure that those are the only imports you are using when in the REPL? The error above is, as it says:
Note that implicit conversions are not applicable because they are ambiguous:
both method PickleOps in package pickling of type [T](picklee: T)pickling.PickleOps[T]
and method pickleOps in trait Ops of type [T](picklee: T)scala.pickling.PickleOps[T]
are possible conversion functions from v.type to ?{def pickle: ?}
So you have at least two implicit conversions, from scala.pickling.PickleOps[T]() and scala.pickling.Ops.pickleOps. This is strange, because PickleOps is not an implicit class.
For me it works (Scala version 2.11.7 Java 1.7.0_79) in a fresh REPL:
scala> import scala.pickling._
scala> import scala.pickling.Defaults._
scala> import binary._
scala> class Xpto { var a = 0D; var b = 0 }
defined class Xpto
scala> val v = new Xpto { a = 1.23; b = 5 }
v: Xpto = cmd5$$anonfun$1$$anon$1#244da0ed
scala> v.pickle
res6: pickleFormat.PickleType = BinaryPickle([0,0,0,23,99,109,100,53,36,36,97,110,111,110,102,117,110,36,49,36,36,97,110,111,110,36,49,63,-13,-82,20,122,-31,71,-82,0,0,0,5])
Great! It runs!
I started a new fresh scala console.
I was using this reference to scala.pickling in build.sbt:
"org.scala-lang" %% "scala-pickling" % "0.10.1"
and now I'm using
"org.scala-lang.modules" %% "scala-pickling" % "0.10.1"
I'm also utilising Scala 2.11.6
Now it works perfectly, and really it's so simple.
scala> import scala.pickling._
import scala.pickling._
scala> import scala.pickling.binary._
import scala.pickling.binary._
scala> import scala.pickling.Defaults._
import scala.pickling.Defaults._
scala> class Xpto { var a = 0D; var b = 0; }
defined class Xpto
scala> val v = new Xpto { a = 1.23; b = 4; }
v: Xpto = $anon$1#1e7bd4df
scala> v.pickle
res0: pickling.binary.pickleFormat.PickleType = BinaryPickle([0,0,0,52,46,108,105,110,101,55,46,46,114,101,97,100,46,46,105,119,46,46,105,119,46,46,105,119,46,46,105,119,46,46,105,119,46,46,105,119,46,46,105,119,46,46,105,119,46,46,97,110,111,110,46,49,63,-13,-82,20,122,-31,71,-82,0,0,0,4])
I don't now if my others libraries references was generating that ambiguous refence. My references in build.sbt are:
libraryDependencies ++= Seq(
"log4j" % "log4j" % "1.2.17",
"javax.transaction" % "jta" % "1.1",
"com.typesafe.akka" %% "akka-actor" % "2.3.10",
"com.typesafe.akka" %% "akka-testkit" % "2.3.10",
"org.scalatest" %% "scalatest" % "3.0.0-SNAP4" % "test",
"org.apache.commons" % "commons-io" % "1.3.2",
"com.typesafe.akka" %% "akka-slf4j" % "2.3.11",
"ch.qos.logback" % "logback-classic" % "1.0.9",
"org.scala-lang.modules" %% "scala-pickling" % "0.10.1"
)
Thanks to Markus.
TL/DR: Checkout last two commits and run sbt clean compile: https://github.com/mirelon/akka-in-action/tree/json/chapter2
There is RestInterface.scala:
package com.goticks
import akka.actor._
import spray.routing._
import spray.http.StatusCodes
import spray.httpx.SprayJsonSupport._
import spray.routing.RequestContext
import akka.util.Timeout
import scala.concurrent.duration._
import scala.language.postfixOps
class RestInterface extends HttpServiceActor
with RestApi {
def receive = runRoute(routes)
}
trait RestApi extends HttpService { actor: Actor =>
import context.dispatcher
import com.goticks.TicketProtocol._
implicit val timeout = Timeout(10 seconds)
import akka.pattern.ask
def routes: Route =
path("events") {
get { requestContext =>
context.actorOf(Props[Resu]).ask(GetEvents)
}
}
}
class Responder(requestContext:RequestContext) extends Actor {
import TicketProtocol._
def receive = {
case Events(events) =>
requestContext.complete(StatusCodes.OK, events)
self ! PoisonPill
}
}
and Resu.scala (note that Resu is alphabetically after RestInterface)
package com.goticks
import akka.actor.Actor
class Resu extends Actor {
import TicketProtocol._
import spray.json._
def receive = {
case GetEvents => {
println(Event(event = "E").toJson)
}
}
}
object TicketProtocol {
import spray.json._
case class Event(event:String)
case object GetEvents
case class Events(events:List[Event])
object Event extends DefaultJsonProtocol {
implicit val format = jsonFormat1(Event.apply)
}
}
build.sbt:
name := "goticks"
version := "0.1-SNAPSHOT"
organization := "com.goticks"
scalaVersion := "2.11.1"
libraryDependencies ++= {
val akkaVersion = "2.3.4"
val sprayVersion = "1.3.1"
Seq(
"com.typesafe.akka" %% "akka-actor" % akkaVersion,
"io.spray" %% "spray-can" % sprayVersion,
"io.spray" %% "spray-routing" % sprayVersion,
"io.spray" %% "spray-json" % "1.2.6"
)
}
build.properties;
sbt.version=0.13.7
plugins.sbt:
resolvers += Classpaths.typesafeResolver
resolvers += "sbt-idea" at "http://mpeltonen.github.com/maven/"
addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.6.0")
addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.11.2")
addSbtPlugin("com.typesafe.sbt" % "sbt-start-script" % "0.10.0")
addSbtPlugin("com.typesafe.sbt" % "sbt-multi-jvm" % "0.3.8")
Compilation issue
When I run sbt clean compile, everything is ok. But when I refactor the Resu class into Ress (note that Ress is alphabetically before RestInterface) (also rename its file, the diff can be viewed here: https://github.com/mirelon/akka-in-action/commit/583ca801fb7d1564024eee2f98d57f03ecacc6e5), then there is a compilation error:
[error] /home/miso/IdeaProjects/akka-in-action/chapter2/src/main/scala/com/goticks/Ress.scala:12: Cannot find JsonWriter or JsonFormat type class for com.goticks.TicketProtocol.Event
[error] println(Event(event = "E").toJson)
[error] ^
[error] one error found
[error] (compile:compile) Compilation failed
Clearly there is an implicit json writer missing. Could it be due to incorrect order of compiling? Could sbt compile the classes in alphabetical order, ignoring imports?
Yes, sbt always compiles in alphabetical order. The issue is sbt has no idea the dependencies between files until it runs the compiler.
What you're seeing is the scala compiler itself is dependent on the ordering of source files. Sbt always sorts source files so you can at least work around these issues by placing code in an ordering that works.
I'm not 100% sure why you're hitting such an issue from some implicits + macro hackery, but that could be wrong.