Compiler Arguments

ponyc, the compiler, is usually called in the project directory, where it finds the .pony files and its dependencies automatically. There it will create the binary based on the directory name. You can override this and tune the compilation with several options as described via ponyc --help and you can pass a separate source directory as an argument.

ponyc [OPTIONS] <package directory>

The most useful options are --debug, --path or just -p, --output or just -o and --docs or -g. With -l you can generate a C library, lib<directory>.

--debug will skip the LLVM optimizations passes. This should not be mixed up with make config=debug, the default make configuration target. config=debug will create DWARF symbols, and add slower assertions to ponyc, but not to the generated binaries. For those, you can omit DWARF symbols with the --strip or -s option.

--path or -p take a : separated path list as the argument and adds those to the compile-time library paths for the linker to find source packages and the native libraries, static or dynamic, being linked at compile-time or via the FFI at run-time. The system adds several paths already, e.g. on windows it queries the registry to find the compiler run-time paths, you can also use use "lib:path" statements in the source code and as a final possibility, you can add -p paths. But if you want the generated binary to accept such a path to find a dynamic library on your client system, you need to handle that in your source code by yourself. See the options package for this.

--output or -o takes a directory name where the final binary is created.

--docs or -g creates a directory of the package with documentation in readthedocs.org format, i.e. markdown with nice navigation.

Let's study the documentation of the builtin stdlib:

  pip install mkdocs
  ponyc packages/stdlib --docs && cd stdlib-docs && mkdocs serve

And point your web browser to http://127.0.0.1:8000 serving a live-reloading local version of the docs.

Note that there is no built-in debugger to interactively step through your program and interpret the results. But ponyc creates proper DWARF symbols and you can step through your programs with a conventional debugger, such as GDB or LLDB.

Runtime options for Pony programs

Besides using the cli package, there are also several built-in options for the generated binary (not for use with ponyc) starting with --pony*, see ponyc --help, to tweak runtime performance. You can override the number of initial threads, tune cycle detection (CD), the garbage collector and even turn off yield, which is not really recommended.