Minimal Clojure environment

This document describes how to set up a minimal Clojure environment under Linux or MacOS.

Java

First, make sure that Java 1.8 ~~or higher~~ is installed. (Note that Java versions greater than 1.8 may not work correctly, so you are best off running 1.8.) If you run

java -version

from the command line, you should see something like the following:

openjdk version "1.8.0_131"
OpenJDK Runtime Environment (build 1.8.0_131-8u131-b11-2ubuntu1.16.04.3-b11)
OpenJDK 64-Bit Server VM (build 25.131-b11, mixed mode)

The exact output isn’t important as long as the version number starts with 1.8.

Leiningen

Start a terminal and run the following commands:

cd $HOME
mkdir -p bin
cd bin
[ -e lein ] && mv lein lein.OLD
wget https://raw.githubusercontent.com/technomancy/leiningen/2.7.1/bin/lein
chmod a+x lein

Configure .bashrc

Edit the .bashrc file in your home directory to add the following lines at the bottom of the file:

export PATH=$HOME/bin:$PATH

Close your existing terminal (if any), start a new terminal, and then run the command

echo $PATH

Make sure you see something like homedir/bin in your $PATH. For example, my home directory is /home/dhovemey, so I would expect to see /home/dhovemey/bin in my $PATH.

Verify leiningen

In your terminal, run the command

which lein

Make sure the output is something like homedir/bin/lein, where homedir is your home directory. When I run this command, I see the output

/home/dhovemey/bin/lein

because my home directory is /home/dhovemey. Important: make sure you do not see /usr/bin/lein.

Next, run the command

lein -version

You should see something like

Leiningen 2.7.1 on Java 1.8.0_131 OpenJDK 64-Bit Server VM

Finally, run the following commands:

cd $HOME
rm -rf .lein

These last commands will clear out any previously cached dependencies and ensure you get a completely fresh Clojure environment.

Using Leiningen

Now run

lein repl

You should be in a Clojure REPL. If this works, you should be able to run Leiningen commands from the command line. For example, let’s say your work on the structured-data MOOC chapter is in $HOME/git/structured-data. To run the tests, you’d do something like

cd $HOME
cd git/structured-data
lein midje