Scala: How can I install a package system wide for working with in the repl?

Question

In Python, if I install a package with pip install package_name, I can open a Python repl by typing python and simply import the package by its name, regardless of what directory I'm currently in in the filesystem.

Like so

$ python
Python 2.7.3 (default, Sep 26 2013, 20:03:06) 
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
>>> 

and the requests library is imported and I can play with it in the repl.

In Scala, I know how to do this in a project that uses sbt, but for learning purposes, I would like to install a package in such a way so that I can simply type scala at the command line and then import the installed package, without being tied to a specific project.

$ scala
Welcome to Scala version 2.10.2 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_40).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import scalaz._
<console>:7: error: not found: value scalaz
       import scalaz._

How can I do this?

Answer 1

Scala is different from Python. Code compiled for Scala 2.9.x is not compatible to 2.10.x. So global definitions can cause a lot of problems if you work with different versions.

You can use SBT and add to $HOME/.sbt/plugins/build.sbt

libraryDependencies += "org.scalaz" %% "scalaz-core" % "7.0.4"

or

libraryDependencies += "org.scalaz" % "scalaz-core_2.10" % "7.0.4"

and then go to /tmp and start a Scala REPL with SBT:

sbt console

But on long term it is not a good idea.

The best thing would be to install SBT, create a file build.sbt and put this in it:

libraryDependencies += "org.scalaz" % "scalaz-core_2.10" % "7.0.4"

scalaVersion := "2.10.2" 

initialCommands in console := "import scalaz._, Scalaz._"

Now change with the console into the folder of build.sbt and run

sbt console

With this you can experiment with the REPL and have already scalaz imported and in the class path. In addition it is easy to add additional dependencies. SBT is cool, you don't need to install new Scala versions manually, just declare it in build.sbt.