ccl (Computation and Control Language) is a small embedded interpreted language used by the gro bacterial-colony simulator to express per-cell programs, world setup, and reactive rules. It is implemented in C++ with a flex/bison parser, and ships as a static library — applications link libccl.a and call readOrganismProgram from ccl.h to load and evaluate .gro source.

brew install cmake bison flex m4         # macOS
# or: sudo apt install cmake bison flex   # Debian/Ubuntu

cmake -S . -B build
cmake --build build -j
# → build/libccl.a

On macOS, the CMake config auto-detects Homebrew's keg-only bison, flex, and m4. Apple's stock /usr/bin/bison is too old (2.3, 2008) and flex 2.6 silently produces an empty lexer with the system m4.