Using LFE

Development environment

# In a project directory (Erlang 21+ and rebar3 required):
$ rebar3 lfe repl

# From the LFE source repo:
$ make && ./bin/lfe

# No install needed:
$ docker run -it lfex/lfe

Once in the REPL, (help) prints available commands and double-tap <TAB> after a module prefix (e.g., (lists:) lists its exported functions.

• Development Setup — installing Erlang + rebar3 + LFE
• The LFE REPL — features, readline, job control, file evaluation
• Creating LFE Projects — project layout and rebar3 conventions
• Emacs lfe-mode — syntax highlighting and REPL integration, bundled with LFE

OTP reference

The modules you'll reach for every day.

;; Calling into OTP is just calling Erlang modules:
lfe> (application:which_applications)
((lfe "Lisp Flavoured Erlang" "2.1.4")
 (compiler "ERTS  CXC 138 10" "8.4.1")
 (kernel "ERTS  CXC 138 10" "9.2.1")
 (stdlib "ERTS  CXC 138 10" "5.2.1"))

• ERTS Reference Manual — the runtime system
• Key modules: erlang, application, supervisor
• Behaviours: gen_server, gen_event, gen_statem
• Data: lists, maps, proplists
• The LFE Machine Manual — Part V: OTP — OTP in LFE

Ecosystem & interop

LFE calls Erlang modules directly — no wrappers, no FFI, no overhead.

;; Any Erlang library is an LFE library:
lfe> (lists:reverse
       (erlang:integer_to_list
         (lists:foldl #'*/2 1 '(1 2 3 4))))
"42"

• Calling Erlang from LFE — the interop model
• Ports and Port Drivers — interfacing with external programs
• Jinterface — Java interop
• rebar3_lfe plugin — the LFE compiler plugin for rebar3
• Community libraries — the LFE ecosystem on GitHub