Is there any way to use scalaz by simple scala command in the terminal, without creating sbt project?
If you have sbt installed, it is relatively quick to setup a scalaz sandbox.
First run sbt:
sbt
Then issue these commands:
set scalaVersion := "2.11.2"
set libraryDependencies += "org.scalaz" %% "scalaz-core" % "7.1.0"
set initialCommands += "import scalaz._, Scalaz._"
session save
console
There you go, you are in the scala REPL with scalaz auto-imported and ready to be used (sbt automatically downloaded scalaz for you).
Because of the command session save, this setup is now permanent and you can at will go back to this same folder and just do sbt console to rerun the REPL with scalaz support.
You can either manually grab the jar or use sbt to grab the jar once and put it in your classpath:
#!/bin/sh
/Users/you/apps/scala/bin/scala -cp /Users/you/.ivy2/cache/org.scalaz/scalaz-core_2.10/bundles/scalaz-core_2.10-7.0.0.jar
Related
I am trying to load an xml file using scala-xml_2.12-1.0.6.jar but it gives me NullPointerEexception while loading
Following is my line of code to load xml
import scala.xml.XML
val xml = XML.loadFile("sample.xml")
I have decompiled this jar and is method is present in that jar but for some reasons it is unable to find it in code.
I have Scala 2.13.1 on my system but for this project I am using scala 2.12.1 and it is mentioned in mu built.sbt
scalaVersion := "2.12.1"
I have following dependency in my built.sbt for this xml package
libraryDependencies += "org.scala-lang.modules" %% "scala-xml" % "1.0.6"
If I copy and paste the same code to Scala interactive shell( scala 2.13.1) I get following error
import scala.xml.XML
^
error: object xml is not a member of package scala
did you mean Nil?
Can anyone please identify what am i doing wrong?
Thanks in advance.
I'm not sure how you are loading up the Scala REPL, but as mentioned in "How to use third party libraries with Scala REPL?", you should be launching the the REPL from SBT with sbt console. Your .sbt files will also need to be in scope.
The Scala REPL independently does not deal with .sbt files. They are 2 different tools.
Alternatively you could also install Ammonite-REPL which supports Magic Imports. You will be able to import Maven dependencies with import $ivy.
Scala 2.12 comes with scala-xml and you can remove that dependency as long as you run REPL with sbt console and not your native Scala REPL which is already # Scala 2.13. Otherwise you can also switch to Scala 2.13 for your SBT project.
I am facing slowness at many places while working with sbt
Importing SBT Project in Intellij -- approx(8-10 minutes).
Indexing in Intellij of SBT Project.
sbt (In terminal this command takes -- approx(2-3 minutes)).
compile (In sbt shell this command takes -- approx(3-5 minutes)).
5.Whenever I modify build.sbt file then project refresh takes 3-4
minutes.
There are more places i need to check but above specified points i am facing frequently.
Is this problem related to SBT or Scala ?, If yes How to resolve the same
Note : I have good internet connection so this cannot be network issue.
My Scala Class file :
import org.scalatest._
class TaskManagerSpec extends FlatSpec with Matchers {
"An empty tasks list" should "have 0 tasks due today" in {
val tasksDueToday = TaskManager.allTasksDueToday(List())
tasksDueToday should have length 0
}
}
build.sbt
name := "tasky"
version := "0.1.0"
scalaVersion := "2.11.6"
resolvers += "Artima Maven Repository" at "http://repo.artima.com/releases"
libraryDependencies += "org.scalatest" %% "scalatest" % "3.0.0" % "test"
SBT is slow because compiles internal code that is done in Scala and Scala compilation is slow because is a complex language (but once Scala is compiled is a lot faster at runtime)
You can give SBT a boost when using SBT 1.x version with the SBT server. The SBT server allows you to use just one SBT instance shared between command line and the IDE. This is pretty useful, more info here: https://www.scala-sbt.org/1.x/docs/sbt-server.html
Also considere using other build tools that are lighter, like PANTS, that is based on Python which is interpreted and a lot faster. More info at: https://www.pantsbuild.org/
NOTE: the PANTS documentation and community is not as extensive as with SBT but is worth the try, there are amazing things that can be done with PANTS.
NOTE2: if your code base is large it will still take a lot of time to compile/build, so considere to arrange your code and artifacts as incremental/cached pieces/subprojects to see a real boost.
I am trying to add Scalding 2.10 as a managed dependency via build.sbt like so:
name := "ss"
version := "1.0"
libraryDependencies += "com.twitter" % "scalding_2.10" % "0.10.0"
IntelliJ downloads the jar and adds it as an external library (see screen below) but fails to resolve the com.twitter namespace.
I have tried both invalidating the IntelliJ cache and generating project files via sbt gen-idea but neither solutions have worked. Any ideas would be greatly appreciated.
The scalding jar file scalding_2.10 has no code in it to compile against. Its just 300 Bytes in size.
The correct dependency I feel should be
libraryDependencies += "com.twitter" % "scalding-core_2.10" % "0.11.1"
As the comment suggest try rm-ing your ivy2 cache, and try sbt gen-idea. If that doesn't work, other things to check:
makes sure you have indeed got the scala plugin installed.
Most likely you're java SDK is not set or pointing somewhere wrong; right click the project dir, click "Open Module Settings", go to SDK and make sure the path is correctly set to the jdk otherwise syntax highlighting will likely break.
To test your deps have been properly pulled in from tinternet, try sbt compile; if it compiles then you should indeed have downloaded the dependency properly.
Trying to learn how to use sbt and stuck with a situation: when I install sbt and run it for the first time, it tries to download scala 2.9.x into some directory inside my home. I have scala 2.10.2 installed somewhere else, so how do I tell sbt to use that scala distribution?
UPD.: Solution (this is distribution for sbt to use when building projects, but sbt will anyway download scala distribution needed for it itself):
***#***:~|⇒ cat .sbt/global.sbt
scalaVersion := "2.10.2"
scalaHome := Some(file("/usr/share/scala"))
You could copy the .jars of your distribution to ~/.ivy2/cache. But that would be totaly missing the point of using sbt. If you want to use scala 2.10.2, just put
scalaVersion := "2.10.2"
into your build.sbt, and it will download this version for you. Then if you want to update to 2.11 when it comes out, all you have to do is change a single line in your build.sbt.
Even after reading: Scala, problem with a jar file, I'm still a bit confused. I am trying to import some packages into my Scala file, and the interpreter is not recognizing them even after adding to classpath.
One example:
I have the import statement:
import org.json4s._
I downloaded the .jar from here: http://mvnrepository.com/artifact/org.json4s/json4s-native_2.10/3.2.4
and added to the interpreter classpath using:
scala> :cp /Users/aspangher13/Downloads/json4s-native_2.10-3.2.4.jar
Scala acknowledges the classpath:
Your new classpath is: ".:/Users/aspangher13/Downloads/json4s-native_2.10-3.2.4.jar:/Users/aspangher13/Downloads/jna-3.5.2.jar"
But still throws this error:
<console>:7: error: object scalatra is not a member of package org
import org.json4s._
Can anyone see what I'm doing wrong? Thanks!!
And as a followup, does anyone know where to find the package: JsonAST._?
Go the simple and create a little sbt project.
First step - create a project
For your purposes you don't need a complex build. So just create two files:
./build.sbt
name := "name your project"
version := "0.1"
scalaVersion := "2.10.2" // or whatever you prefer
./project/build.properties
sbt.version=0.12.4
The just go to the project root folder and call sbt
Second step - add dependencies
Open your ./build.sbt file and add:
libraryDependency ++= Seq(
"org.scalatra" %% "scalatra" % "2.2.1",
"org.scalatra" %% "scalatra-scalate" % "2.2.1",
"org.scalatra" %% "scalatra-specs2" % "2.2.1" % "test",
"org.json4s" %% "json4s-native % "3.2.4",
"net.java.dev.jna" & "jna" & "3.5.2"
)
Step three - run the console
Don't forget to reload sbt with reload task, and then call console or console-quick task. This should work.
But there are easier ways to do this:
1) Use gitter8 - Scalatra gitter8 project
2) Read little into about Scalatra sbt dependencies
Still not sure how :cp works but if you execute
scala -classpath "list of jars colon separated"
then inside the REPL do your imports it should work
import org.json4s._
import org.xyz
However, when you try to use the classes you are likely to be missing transitive dependencies required by json4s and so we come back to the sbt example # 4lex1v describes, which will handle this. Creating a little project and running sbt console will indeed greatly simplify this.
Seems like the -classpath and :cp are primarily meant to make your code available in the shell and then only if you understand all of the transitive dependencies, or have none.