AI heritage revived

Poplog

We brought Poplog — the classic multi-language AI development environment (Pop-11, Prolog, Common Lisp, Standard ML) — natively onto Apple Silicon, Raspberry Pi 5, and RISC-V. Then we added a fifth language, a real ELIZA, native graphics, and a full benchmark suite.

Source on GitHub Read launch story

What it is

Poplog is one of the great artifacts of AI history — a multi-language software development environment from the University of Sussex, built around fast incremental compilers for four interactive languages that share one virtual machine and one saved image, and interoperate freely:

  • Pop-11 — the core language, with the Objectclass OO extension (a CLOS-for-Pop),
  • Prolog — standard Edinburgh syntax,
  • Common Lisp — CLTL2-compatible,
  • Standard ML — strongly typed, polymorphic, functional.

It ran a generation of AI and cognitive-science teaching, then largely fell off the modern platform map. We brought it back — natively — to the silicon people actually have in 2026, and then pushed it further than the original ever went. The work builds on W. Hebisch’s Poplog sources, with a great deal of history reconstructed by hand from the Internet Archive and scattered corners of the web — and it was carried out with Claude as a pair-porting partner, right down into the assembler.

Three new native ports

Poplog compiles to real machine code on every backend, so a port isn’t a recompile — it’s a code generator, a frame contract, and an instruction-cache story per architecture. We landed three:

  • Apple Silicon / macOS (arm64) — a native Mach-O port. Self-hosting, all four languages, terminal VED, C↔Pop callbacks, ad-hoc signed with no entitlements required.
  • Raspberry Pi 5 / AArch64 Linux — validated on the Pi 5 (all four languages + saved images), written to the generic armv8-a baseline so it ports readily to other ARM64 boards.
  • RISC-V / riscv64 Linux — a native RV64GC port, self-hosting on a StarFive VisionFive (dual SiFive U74). All four languages, saved images, terminal VED, and the FFI float ABI; the validation suite runs 14/14.

A fifth language: Forth

Classic Poplog ships four languages. We added a fifth — Forth — as a first-class subsystem. It leans on Poplog’s open-stack calling convention so the implementation stays tiny and genuinely native: Forth’s data stack is the Poplog user stack, and colon definitions (: name … ;) compile through Poplog’s incremental compiler to machine code — a Forth word is a real native procedure, not threaded interpreted code. .fth is a recognized file type and uses forth; drops you into a REPL alongside Pop-11, Lisp, Prolog, and ML. Its built-in testbench is 21/21 on macOS arm64 and RISC-V, and because it’s pure Pop-11 it runs on every platform Poplog does.

A real ELIZA

We added a faithful implementation of Joseph Weizenbaum’s original ELIZA / DOCTOR (MIT, 1966) — not the thin teaching pattern-matcher usually shown, but the genuine engine: keyword ranking, decomposition rules with wildcards and synonym classes, round-robin reassembly templates, first/second-person reflection, keyword redirection, and memory. It’s written in Pop-11 (an unusually good host for it) and validated against Weizenbaum’s original 1966 script. Chat with it locally via tools/eliza.sh.

Native graphics (experimental)

Poplog’s graphics were historically welded to the X window system. We added an optional native backend built on Dear ImGui: Metal + Cocoa on macOS (no X server, no XQuartz) and SDL3 + OpenGL3 on macOS or Linux — SDL3 picks Wayland, X11, or KMS/DRM at run time, so there’s no hard X11 dependency, and it even renders headless via Mesa software for CI. The classic rc_graphic turtle library is ported on top, so existing Pop-11 graphics code runs unchanged. Demos include the classic 10 PRINT maze and a vsync-paced spinning 3D cube.

Porting knowledge, written down

A port is only worth as much as the next person can reuse. We shipped an unusually deep set of notes — a porting recipe, a guide to hosting a new language on the VM, the AArch64 frame contract, RISC-V porting notes, and forensic write-ups of specific codegen bugs (false-label leaks, tail-subtract high-word, stale I-cache SIGILLs) — so the next architecture is a documented walk, not an archaeology dig.

Benchmarks

We published a rigorous benchmark suite: engine micro-benchmarks (calls, arithmetic, allocation/GC, incremental compilation, closures, strings) as the median of 30 runs with bootstrap 95% confidence intervals, across five machines — Intel i7, Apple M2, Apple M5 Pro, Raspberry Pi 5, and the RISC-V VisionFive — with Python and Perl baselines. A representative result: Poplog runtime-compiles a procedure to machine code in ~5.5 ms on an M5 Pro — parity with, or faster than, interpreters merely building bytecode.

Status

Active. A self-contained Nix flake builds and bootstraps the whole system — all five front-ends and their saved images — from source (nix build .#poplog, or .#poplog-gfx for the graphics variant). Source, ports, docs, and benchmarks on github.com/IoTone.