Add List Functions For A Module as an elixir til

elixir/list-functions-for-a-module.md

@@ -0,0 +1,25 @@
+# List Functions For A Module
+
+During an `iex` session, I can do a little introspection on modules using
+either the
+[`__info__/1`](http://elixir-lang.org/docs/stable/elixir/Module.html#__info__/1)
+function or Erlang's
+[`module_info/0`](http://erlang.org/doc/man/erlang.html#module_info-0)
+function. In particular, I can pass `:functions` to either one to get a list
+of the functions for that module.
+
+This is what the `__info__/1` looks like for the functions of the `List`
+module:
+
+```elixir
+> List.__info__(:functions)
+[delete: 2, delete_at: 2, duplicate: 2, first: 1,
+ flatten: 1, flatten: 2, foldl: 3, foldr: 3, insert_at: 3,
+ keydelete: 3, keyfind: 3, keyfind: 4, keymember?: 3,
+ keyreplace: 4, keysort: 2, keystore: 4, keytake: 3,
+ last: 1, replace_at: 3, to_atom: 1, to_existing_atom: 1,
+ to_float: 1, to_integer: 1, to_integer: 2, to_string: 1,
+ to_tuple: 1, update_at: 3, wrap: 1, zip: 1]
+```
+
+[source](http://stackoverflow.com/questions/28664119/in-elixir-is-there-any-way-to-get-a-module-to-list-its-functions)