REPL Me Up!

Make sure you've cded into your new LFE project directory, and then do this:

$ rebar3 lfe repl

This should give you something that looks like the following:

Erlang/OTP 23 [erts-11.0.2] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [hipe] [dtrace]

   ..-~.~_~---..
  (      \\     )    |   A Lisp-2+ on the Erlang VM
  |`-.._/_\\_.-':    |   Type (help) for usage info.
  |         g |_ \   |
  |        n    | |  |   Docs: http://docs.lfe.io/
  |       a    / /   |   Source: http://github.com/rvirding/lfe
   \     l    |_/    |
    \   r     /      |   LFE v1.3-dev (abort with ^G)
     `-E___.-'

lfe>

Try setting a variable:

> (set my-list (lists:seq 1 6))
(1 2 3 4 5 6)

Here are some operations using more functions from the built-in Erlang lists module:

> (* 2 (lists:sum my-list))
42
> (* 2 (lists:foldl (lambda (n acc) (+ n acc)) 0 my-list))
42

Let's turn that into a function:

> (defun my-sum (start stop)
    (let ((my-list (lists:seq start stop)))
      (* 2 (lists:foldl
             (lambda (n acc)
               (+ n acc))
             0 my-list))))
my-sum

And try it out!

> (my-sum 1 6)
42

Enough with the fancy REPL-play ... What about some real code? What does a project look like?