Getting Set Up

If you're new to LFE and haven't read the LFE Quick Start, that might be a good idea to do that -- you'll feel much more comfortable with the material in this book if you have. If you never encountered a Lisp before, or if your familiarity is rusty, we'd recommend reading through the original Casting SPELs in Lisp. That version is more accessible to the Lisp new-comer.


Here's what you need before we get started (links are to more resources, should you be missing any of them):

  • Erlang needs to be installed on your system (download)
  • You need to have git
  • Developer/build tools for your system (in particular, make; instructions for this are very different between systems and can be found on the Web by searching for "install developer tools" or "build essential" for your operating system)

Getting and Building LFE

Once all of the above are set up on your system, you're ready to get LFE:

$ mkdir -p ~/lab
$ cd ~/lab
$ git clone
$ cd lfe
$ make

Starting the REPL

Are you ready? Oh, the REPL? That's an acronym that stands for read-eval-print loop -- it's where you can type LFE code interactively. Let's start it up!

$ ./bin/lfe
Erlang/OTP 18 [erts-7.3] [source] [64-bit] [smp:4:4] [async-threads:10]

  (      \\     )    |   A Lisp-2+ on the Erlang VM
  |`-.._/_\\_.-';    |   Type (help) for usage info.
  |         g (_ \   |   
  |        n    | |  |   Docs: 
  (       a    / /   |   Source:
   \     l    (_/    |   
    \   r     /      |   LFE v1.0 (abort with ^G)


We'll use it more soon, but for now you can try out a little addition:

> (+ 2 2)

We'll be writing our whole adventure game here in the REPL :-) Things should go very smoothly, but if you start exploring and things go nuts, you can reset your REPL to its default clean state with this command:

> (reset-environment)

Keep in mind, though, this will clean everything up! You'll have to start over again!