Examples and recipes

The Beans repository ships a folder of example programs under examples/. Each one is a real, runnable .b file that shows one part of the language. This page tells you how to run them and points you at the ones worth reading.

How to run an example

Point beansc run at a file:

beansc run examples/hello.b

Most examples work through both beansc run (the interpreter) and beansc build (a native binary), and give the same output either way.

The multi-package example is a project, so run it from its main.b:

beansc run examples/shop/main.b

Some examples are target-gated: they need a special target or CPU and will not run on a plain desktop build. Those are marked below.

Language basics

Example	Shows	Runnable
hello.b	Hello world and string interpolation	yes
tour.b	A one-file tour of every language idea	yes

Walked through in Hello and the tour.

Object-oriented code and value types

Example	Shows	Runnable
oop_classes.b	priv methods and fields, static fields, abstract methods, interfaces, and a singleton	yes
generic_structs.b	Generic structs, defaults, read methods, inout fn, and static factories	yes

Walked through in OOP classes and value types.

Concurrency

Example	Shows	Runnable
threads.b	OS threads, generics, enums, Option/Result, decimal	yes
atomics.b	Typed Atomic<T> with explicit MemoryOrder	yes
wide_concurrency.b	Struct and enum values across channels	yes
wide_sync.b	Struct and enum values through a Mutex	yes

Walked through in Threads and channels and Atomics.

Files and storage

Example	Shows	Runnable
files.b	File/Dir statics, positional I/O, errors	yes
reader.b	Buffered line reading	yes
kv.b	Append-only key-value store with durable commit	yes
locks.b	Advisory file locks (flock), single-writer pattern	yes
mmap.b	Whole-file memory mapping	yes
shared_memory.b	POSIX shared memory as an MMap	yes

Walked through in Files and a KV store.

Networking

Example	Shows	Runnable
net.b	TCP and UDP on loopback in one process	yes
poller.b	Waiting on many descriptors (epoll/kqueue)	yes
signals.b	Signals as data, via the poller	yes

Walked through in Networking.

C interop and low-level

Example	Shows	Runnable
ffi.b	extern "C" calls to libc, RawPtr in unsafe	yes
c_layout_structs.b	extern "C" struct layout	yes
c_layout_unions.b	extern "C" union layout	yes
dynamic_library.b	Load a shared library at run time, call an address	yes (needs a library to load)
packed.b	packed and align(N)	yes
layout.b	size_of / align_of / offset_of	yes
raw_slices.b	Slice<T>	yes
unsafe_raw.b	RawPtr null / alloc / offset / read / write	yes

Walked through in C interop (FFI).

Memory and ownership

Example	Shows	Runnable
box.b	Generic move-only handles	yes
arena.b	Generic move-only handles	yes
shared_weak.b	Shared and Weak	yes
ordered_map.b	OrderedMap	yes
cycles.b	Reference cycles freed by the collector	yes
ctors.b	The init / deinit contract	yes
generic_deinit.b	A generic class with deinit and a closure factory	yes

Processes, time, and the machine

Example	Shows	Runnable
child_process.b	Command.start() returning a Child (uses async)	yes
processes.b	Command.run()	yes
clocks_random.b	Time and random	yes
cpu_dispatch.b	cpu.has and a feature-gated function	yes (feature-gated code needs the CPU feature)
intrinsics.b	std.intrinsic	yes
inline_asm.b	std.asm	yes
target_info.b	std.target	yes

SIMD

Example	Shows	Runnable
simd.b	Simd4f32 fused multiply-add	yes (some SIMD needs CPU features)
simd_families.b	SIMD family naming, width and feature rules	yes (some SIMD needs CPU features)

Standard library tours

Example	Shows	Runnable
fmt.b	std.fmt	yes
strings.b	String operations	yes
bytes.b	Bytes operations	yes
containers.b	Collections	yes
stdlib_beans.b	A stdlib tour	yes

Some of these tours end in a deliberate panic. That is part of their job as a test.

Multi-package project

Example	Shows	Runnable
shop/	Three packages, cross-package interfaces and generics	yes, via examples/shop/main.b

Walked through in A local-package project.

Target-gated examples

These need a specific target or runtime and will not run on a plain desktop build:

Example	Needs
embedded.b	A 32-bit no-OS target (decimal is refused there)
freestanding.b	--runtime freestanding

The language guide covers every feature in order, and the builtin reference and standard library reference are there to look things up.