Run `fun -i` (or run `fun` without a script, depending on version). See [REPL](/documentation/repl/).
## Which build target should I use?
Use the aggregate `build` target to build `fun`, `fun_test`, and `test_opcodes`. See [Build](/documentation/build/).
## Where are the standard libraries?
Under [https://git.xw3.org/fun/fun/src/branch/main/lib](https://git.xw3.org/fun/fun/src/branch/main/lib){:class="git"}. See [stdlib](/documentation/stdlib/) for an overview.
## Where can I find internals and opcodes?
Browse [https://git.xw3.org/fun/fun/src/branch/main/src/vm](https://git.xw3.org/fun/fun/src/branch/main/src/vm/) and [Internals](/documentation/internals/) / [Opcodes](/documentation/opcodes/).