Prolog · version 9

Run Prolog 9 online

Prolog 9 — run it in a Firecracker microVM on ls-judge. Real toolchain, no wrapper.

Starter code

What you get in Prolog 9

Clicking "Run now" opens the playground with this exact code and a matching test case — passes on first Run.

prolog
Prolog 9
main :- read_term(N, []), N2 is N * 2, write(N2), nl.
stdin →21.
expected →42
How it runs

How ls-judge runs Prolog 9

Every submission is compiled and executed inside its own Firecracker microVM — the same isolation primitive AWS Lambda uses. No shared container, no shared kernel with other users' code. The Prolog 9toolchain shipped with the microVM is the real thing (not a browser-side emulation): syscalls behave the way they do in production, and the compile / runtime behaviour matches what you would see on your own machine with that version installed.

Feed stdin from the Tests panel, watch verdicts stream per test case over a WebSocket. Free to use, no sign-up, works from any browser.