The Erlang Standard Library
man Pages and Online Docs
Erlang has a lot of standard modules to help you do things which are directly callable from LFE. For example, the module io contains a lot of functions to help you perform various acts of formatted input/output. Depending upon your Erlang installation, you may have man pages available. From your operating system shell, you can found out by typing erl -man <module name> like so:
erl -man io
If you have man pages installed, that command would give output along these lines:
ERLANG MODULE DEFINITION io(3)
MODULE
io - Standard I/O Server Interface Functions
DESCRIPTION
This module provides an interface to standard Erlang IO
servers. The output functions all return ok if they are suc-
...
If your installation of Erlang doesn't have man pages, you can always find what you're looking for on the documentation web site. Here is the online man page for the io module.
Module and Function Tab-Completion in the REPL
From the LFE REPL, you have some other nice options for standard library discovery. Start up LFE to take a look:
./bin/lfe
Erlang/OTP 23 [erts-11.0.2] [source] [64-bit] [smp:12:12] ...
lfe>
Now, at the prompt, hit your <TAB> key. You should see something like this:
application application_controller application_master
beam_lib binary c
code code_server edlin
edlin_expand epp erl_distribution
erl_eval erl_parse erl_prim_loader
erl_scan erlang error_handler
error_logger error_logger_tty_h erts_internal
ets file file_io_server
file_server filename gb_sets
gb_trees gen gen_event
gen_server global global_group
group heart hipe_unified_loader
inet inet_config inet_db
inet_parse inet_udp init
io io_lib io_lib_format
kernel kernel_config lfe_env
lfe_eval lfe_init lfe_io
lfe_shell lists net_kernel
orddict os otp_ring0
prim_eval prim_file prim_inet
prim_zip proc_lib proplists
ram_file rpc standard_error
supervisor supervisor_bridge sys
unicode user_drv user_sup
zlib
These are all the modules available to you by default in the LFE REPL. Now type (g and hit <TAB>:
lfe> (g
gb_sets gb_trees gen gen_event
gen_server global global_group group
Let's keep going! Continue typing a full module, and then hit <TAB> again:
lfe> (gb_trees:
add/2 add_element/2 balance/1 del_element/2
delete/2 delete_any/2 difference/2 empty/0
filter/2 fold/3 from_list/1 from_ordset/1
insert/2 intersection/1 intersection/2 is_disjoint/2
is_element/2 is_empty/1 is_member/2 is_set/1
is_subset/2 iterator/1 largest/1 module_info/0
module_info/1 new/0 next/1 singleton/1
size/1 smallest/1 subtract/2 take_largest/1
take_smallest/1 to_list/1 union/1 union/2
Now you can see all the functions that are available in the module you have selected. This is a great feature, allowing for easy use as well as exploration and discovery.