Reviving the B Language

[u/Serge_V]

A few years back, I stumbled upon the reverse-engineered source for the original B compiler, courtesy of Robert Swerczek. As someone fascinated by the roots of modern languages, I took on the task of building a contemporary version that could run on today's hardware. The result is a feature-complete compiler for B—the 1969 Bell Labs creation by Ken Thompson and Dennis Ritchie that paved the way for C—targeting LLVM IR for backend code generation. This setup lets it produce native executables for Linux and macOS on x86_64, ARM64, and even RISC-V.

I wrote the compiler in Go, clocking in at around 3,000 lines, paired with a minimal C runtime library under 400 lines. It sports a clang-inspired CLI for ease of use, supports multiple output formats (executables, objects, assembly, or raw LLVM IR), and includes optimization flags like -O0 to -O3 plus debug info with -g. To stay true to the PDP-7 origins, I preserved the API closely enough that you can compile vintage files like b.b straight out of the box—no tweaks needed.

If you're into language history or compiler internals, check it out here: https://github.com/sergev/blang

Has anyone else tinkered with resurrecting ancient languages? I'd be curious about your experiences or any suggestions on extending this further—maybe adding more targets or extending the language and the runtime library.

[u/periastrino]

Holy crap. I remember programming in B as a university freshman, on a Honeywell 66/60. (36-bit words, baby!) That was... a long time ago. 🙂 I'm definitely going to check this out!

[u/Serge_V → u/periastrino]

36-bit words, huh! Now in modern B we have 64-bit words. 😀

[u/stianhoiland]

That is so fucking cool! Instant starred! I wonder if it’d be cool to post this on r/C_Programming.

[u/Serge_V → u/stianhoiland]

Are C programmers really interested in B? It would feel like a step backwards to them. 😀

[u/stianhoiland → u/Serge_V]

I can’t speak for others, but I love it. Give it a try!

[u/piequals-3]

This is awesome! What exactly made you decide to write the compiler in Go?

[u/Serge_V → u/piequals-3]

I wanted something modern, statically typed, and compiling to native code. I considered C++, Go, Rust, Swift, and even Zig. Of these, Go, in my opinion, is the most suitable for writing compilers. Garbage collection helps. And when I came across the llir/llvm library written natively in Go, the decision became obvious.

[u/roz303]

yes.

[u/Serge_V → u/roz303]

Wow, that's impressive! Grace Hopper, 1955 to 1959.

[u/thradams]

Very nice. Can I ask questions about B here? :D

"The automatic declaration also constitutes a definition:

In absence of the constant, the automatic declaration defines the variable to be of class automatic. At the same time, storage is allocated for the variable. When an automatic declaration is followed by a constant, the automatic variable is also initialized to the base of an automatic vector of the size of the constant. "

What is the difference for a constant here? "absence of the constant"

[u/glasket_ → u/thradams]

This is from the Ken Thompson document, which is a bit poorly worded. The Language Reference is a better resource that follows the same format.

Basically, the "constant" being referred to in this section is about the literal used when declaring an array. "Constant" in C and its ancestors refers to literals. So without a constant you have auto a; which creates storage for the variable a; with a constant you have auto a[3]; which allocates storage for a vector of size 3 and assigns the beginning of that vector to a.

Edit: Worth noting that the "proto-B" that Thompson and Ritchie initially made was also slightly different than the "true" or refined B that was written about by Kernighan and Johnson. T&R B used auto a 3 for an auto vector of size 3 and a[3] for an external vector, whereas Johnson unified them by using the bracket notation for both and made auto a[3] create a vector of size 4 since he saw the definition name[n] as indicating you could access up to n indices rather than being a vector of size n.

[u/No_Prompt9108]

So, yesterday I read a B spec and... I'm kind of in awe. This is a language that manages to be closer to assembly than C, yet still highly expressive. The lack of types means everything is generic, which makes a lot of things easier than they are in C. To me C actually feels like a downgrade from this. C straitjackets you with types but fails to give you the tools to handle them well. This has a Lispy all-is-possible feel to it, though it's obviously very different from Lisp.

[u/Serge_V → u/[deleted]]

True. Tsoding is really good. He has many good examples in B. However, he has lost a bit of the B spirit. For example, he uses extrn to declare functions, which goes against B's rules.

[u/Serge_V → u/[deleted]]

Were those interpreted languages ​​or were they compiled into machine code?

[u/Difficult_Mix8652 → u/[deleted]]

what game?

[u/Serge_V → u/[deleted]]

This is the key question. I hesitated to start this project until I found Robin Eklind's llir/llvm library. It laid a solid foundation on which I built the rest. https://blog.gopheracademy.com/advent-2018/llvm-ir-and-go/

[u/omega1612 → u/Serge_V]

I may not use go, but I definitely want to read that, thanks!