fun/web/documentation/build/build.md

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page	true	false	false	false	Building Fun	How to build Fun with CMake, available targets, and build options (FUN_DEBUG, FUN_USE_MUSL, FUN_WITH_CPP, FUN_WITH_RUST, FUN_WITH_OPENSSL).	How to build Fun with CMake, available targets, and build options (FUN_DEBUG, FUN_USE_MUSL, FUN_WITH_CPP, FUN_WITH_RUST, FUN_WITH_OPENSSL).	/documentation/build/	en	available build building cmake fun_debug fun_use_musl fun_with_cpp fun_with_openssl fun_with_rust options targets

This guide describes how to build Fun from source using CMake and the available build options.

Prerequisites

• A C compiler with C99 support
• CMake 3.20+ (or newer)
• Optional: Rust toolchain with cargo (required when building with FUN_WITH_RUST=ON)

Common targets

• build - aggregate target that depends on fun, fun_test, and test_opcodes
• fun - the CLI executable
• fun_test - unit/feature tests (run with CTest)
• test_opcodes - opcode tests (executable)

These targets are defined by the project; use your configured CMake build directory/profile.

Build options

Fun exposes several options you can toggle at configure time:

• FUN_DEBUG (ON/OFF) - Enables extra assertions and logging in the VM and runtime
• FUN_USE_MUSL (ON/OFF) - Link against musl for static/portable builds (Linux)
• FUN_WITH_CPP (ON/OFF) - Enable C++-based opcode/examples support
• FUN_WITH_RUST (ON/OFF) - Build and link Rust staticlib from src/rust/
• FUN_WITH_OPENSSL (ON/OFF) - Enable OpenSSL-backed helpers (MD5/SHA-256/SHA-512/RIPEMD-160)

VM configuration constants

You can override internal VM limits at compile time by passing -D<VAR>=<VALUE> to CMake:

• MAX_FRAMES (default: 128) - Maximum depth of the call stack (frames)
• MAX_FRAME_LOCALS (default: 64) - Maximum number of local variables per frame
• MAX_GLOBALS (default: 128) - Maximum number of global variables
• OUTPUT_SIZE (default: 1024) - Size of the VM output buffer (number of values)
• STACK_SIZE (default: 1024) - Size of the VM evaluation stack (number of Value slots)

These are defined as CACHE variables, so they will persist in your CMakeCache.txt.

When configuring, the build prints a summary like:

See VM for more information.

==== Fun build options ====
  FUN_DEBUG: ENABLED|DISABLED
  FUN_USE_MUSL: ENABLED|DISABLED
  FUN_WITH_CPP: ENABLED|DISABLED
  FUN_WITH_RUST: ENABLED|DISABLED
===========================

Example commands

Use the CLion-provided build directories or your own. Typical invocations:

Debug

cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug \
  -DFUN_DEBUG=ON -DFUN_WITH_RUST=OFF
cmake --build build --target build

Release

cmake -S . -B build_release -DCMAKE_BUILD_TYPE=Release \
  -DFUN_DEBUG=OFF -DFUN_WITH_RUST=OFF
cmake --build build_release --target build

Enabling optional extensions

cmake -S . -B build_release -DCMAKE_BUILD_TYPE=Release \
  -DFUN_WITH_CPP=ON -DFUN_WITH_RUST=ON -DFUN_WITH_OPENSSL=ON
cmake --build build_release --target build

Customizing VM limits

cmake -S . -B build_custom -DSTACK_SIZE=4096 -DMAX_GLOBALS=512
cmake --build build_custom --target fun

If FUN_WITH_RUST is enabled, ensure cargo is available in PATH; the build will invoke it and link the produced static library.

If FUN_WITH_OPENSSL is enabled, CMake must detect your system OpenSSL (libcrypto).

Running

• CLI: run the fun executable from your build directory.
• REPL: fun -i or just run fun without a script, depending on your CLI version (see CLI).
• Examples: see Examples.

Tip: When running from the repository without installation, set FUN_LIB_DIR to the local ./lib so includes can find the stdlib.