Better C (BC)

BC is a system-level programming language inspired by C, but designed to be safer, more expressive, and more modern—while staying true to the spirit of freestanding, low-level control.

It currently transpiles to LLVM IR manually, with plans to support C and assembly output as well. The runtime is optional and minimal, written in C or LLVM IR, and designed to work without libc (-nostdlib, -ffreestanding). You can build raw executables, call syscalls directly, and write low-level code without being boxed in.

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¨ Why Better C?

C is powerful but clunky. BC keeps the power, drops the clunk.

• No preprocessor nonsense.
• No undefined behavior from ancient legacy.
• No standard library unless you want one.
• Explicit, readable syntax.
• Designed for freestanding, bare-metal, and systems programming.
• You write code BC turns it into clean LLVM IR you control the final binary.

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Current Status

• Lexing
• Parsing into AST
• Manual LLVM IR Codegen
• Variable bindings
• let definitions
• Type annotations (i32, void, etc)
• Function definitions
• LLVM IR output that can be compiled with llc + ld

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Example

Input (BC source):

extrn fn putint(i i32) void;

fn main() void {
    let v i32 = 39;
    putint(v);
}

Output (LLVM IR):

declare void @putint(i32)

define void @main() {
entry:
    %v = alloca i32
    store i32 39, ptr %v
    %tmp = load i32, ptr %v
    call void @putint(i32 %tmp)
    ret void
}

Compile with:

llc out.ll -o out.s
ld -o a.out out.s bc/runtime/start.o bc/runtime/runtime.o
./a.out

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Toolchain

• Language written in D.
• Compiler manually emits LLVM IR.
• Runtime is minimal and located in bc/runtime/.
• Only required dependencies: runtime.o and start.o for linking.

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Design Goals

BC aims to be:

• Freestanding-first: works without libc.
• Predictable: no hidden allocations, no magic behaviors.
• Modern: inspired by Rust, and Odin but compiles down to clean, raw output.
• Extensible: eventual plans for modules, generics, and user-defined memory management.

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File Extensions

BC source files use .bc (coincidentally also the LLVM bitcode extension).
I may change this later if needed, but for now: .bc it is.

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Roadmap (short-term)

• Type checker
• Argument support for functions
• Runtime function declarations
• External function imports (extrn fn ...)
• String handling in IR
• Variadic arguments via slice-style packing
• Build system (no make, no cmake, just bc build)

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Contributing / Hacking

Right now this is mostly a solo project by me, and you're welcome to fork or follow progress.

To build:

dub run

To test:

./bc example.bc
llc out.ll -o out.s
ld -o a.out out.s bc/runtime/start.o bc/runtime/runtime.o
./a.out