c-rogueutil

RogueUtil Haskell Bindings

This example demonstrates generating Haskell bindings for the rogueutil library, a cross-platform C library for terminal manipulation.

Quirks and Workarounds

1. Disabling Shared Libraries (shared: False)

The generate-and-run.sh script sets shared: False in cabal.project.local to prevent duplicate symbol errors during compilation.

Why this is needed:

RogueUtil is an unusual C library that defines function implementations directly in the header file (rogueutil.h) rather than in separate .c files. This is unorthodox C practice, but allows rogueutil to be a header-only library.

When hs-bindgen generates bindings for such a library, it creates C wrapper functions that get embedded into multiple generated modules (Safe, Unsafe, FunPtr, Global). During dynamic library compilation, each module includes its own copy of these wrappers, causing "multiple definition" linker errors like:

ld: error: multiple definition of 'printXY'

Setting shared: False disables dynamic library building, preventing these conflicts. Static linking only includes each symbol once, avoiding the duplication problem.

2. Enabling Modern C Standard (-D_POSIX_C_SOURCE=200809L)

The binding generation command includes the clang option -D_POSIX_C_SOURCE=200809L:

--clang-option=-D_POSIX_C_SOURCE=200809L

This enables POSIX.1-2008 features that rogueutil depends on (such as usleep, nanosleep, and terminal control functions). Without this flag, clang would fail to parse the header due to missing standard library declarations.

Running the Example

./generate-and-run.sh