How to deploy an open-source APL interpreter on Linux with verification and rollback steps

Follow these steps to deploy an open‑source APL interpreter on a Linux system.

1. Choose an implementation. For a fully featured, standards‑compliant option install GNU APL; for a lightweight, browser‑friendly version try ngn/APL.
2. Install dependencies. GNU APL requires a C compiler and the libncurses5-dev (or equivalent) package. ngn/APL needs Node.js and CoffeeScript.
3. Obtain the source. Download the latest tarball from the GNU APL repository or clone the ngn/APL GitHub repository.
4. Build and install. For GNU APL run ./configure && make && sudo make install. For ngn/APL run npm install followed by npm run build.
5. Verify the installation. Execute a simple APL expression, e.g. echo '1 2 3 + 4 5 6' | apl should output 5 7 9. For ngn/APL launch the REPL and type 1 2 3 + 4 5 6.
6. Rollback if needed. If you installed via make install, run sudo make uninstall in the build directory or remove the files manually. For package‑based installations use your distribution’s package manager (e.g., sudo apt remove gnuapl). For ngn/APL delete the cloned directory and any global npm links.

Each step can be repeated or skipped according to the chosen implementation.