mixmux lets you treat a running iex session sort of like an administrative shell on a Unix system, where you can tell the running system to reconfigure itself by installing/removing packages.
Typing some commands and realize that you need a package?
iex(3)> Jazz.encode [1, "2", [3]]
** (UndefinedFunctionError) undefined function: Jazz.encode/1 (module Jazz is not available)
Jazz.encode([1, "2", [3]])
Just tell Mixmux to start the application, as if it was already available:
iex(3)> Mixmux.start :jazz
==> mixmux_mockapp
Running dependency resolution
Unlocked: jazz
Dependency resolution completed successfully
jazz: v0.2.1
* Getting jazz (package)
Checking package (http://s3.hex.pm/tarballs/jazz-0.2.1.tar)
Fetched package
Unpacked package tarball (/root/.hex/packages/jazz-0.2.1.tar)
==> jazz
Compiled lib/jazz.ex
Compiled lib/jazz/parser.ex
Compiled lib/jazz/decoder.ex
Compiled lib/jazz/encoder.ex
Generated jazz.app
:ok
iex(4)> Jazz.encode [1, "2", [3]]
{:ok, "[1,\"2\",[3]]"}
You can remove packages as well (thus allowing a limited form of upgrading):
iex(6)> Mixmux.remove :jazz
01:16:45.069 [info] Application jazz exited: :stopped
==> mixmux_mockapp
* Cleaning jazz
:ok
iex(7)> Jazz.encode [1, "2", [3]]
** (UndefinedFunctionError) undefined function: Jazz.encode/1 (module Jazz is not available)
Jazz.encode([1, "2", [3]])
mixmux's installed packages, and their build files, are kept separate from your regular mix deps and build files. Deps retrieved by mixmux appear in the mixmux/ directory, and build into the _build/mixmux/ directory.