wll-interface is a header only library written in C++. It effectively abstracts Wolfram LibraryLink, greatly simplifying the process of loading external functions.

wll-interface is most useful in these scenarios:

1. I want to write a function in C++ for better performance and load it into Mathematica
2. I want to call an external library with C/C++ API from Mathematica

Prerequites and Installation

To use wll-interface, you need:

• Mathematica 10 or later
• C++ compiler that covers most of the C++17 features
  • GCC 7 or later
  • Clang 4 or later
  • MSVC 19.11 (Visual Studio 2017 15.3) or later
  • ICC 19.0 or later

For more information about setting up compilers, see the documentation page for CCompilerDriver Specific Compilers

To install wll-interface, simply download wll_interface.h. The path to the file will be used later.

Documentation

See the Wiki to get started.

Neat example

In this example, we are going to load a C++ function multiply into Mathmatica.

To use wll-interface with C++ code, you need to include the header file and use DEFINE_WLL_FUNCTION macro to defined the function to be exported:

src = "
#include \"wll_interface.h\"

double multiply(double x, int y)
{
    return x * y;
}

DEFINE_WLL_FUNCTION(multiply)  // defines wll_multiply
";

A new function wll_multiply is defined automatically by the library, which is going to be compiled and loaded.

Now we create a shared library from the code. You need to replace <path-to-wll_interface.h> below with the directory that contains the header file wll_interface.h so that the compiler can find it.

Needs["CCompilerDriver`"];
mylib = CreateLibrary[src, "wll_multiply", 
  "IncludeDirectories" -> {"<path-to-wll_interface.h>"}, 
  Language -> "C++", "CompileOptions" -> "-std=c++17"]

Finally, we load the function into Mathematica, and use it:

multiply = LibraryFunctionLoad[
  mylib, "wll_multiply", {Real, Integer}, Real];
multiply[2.33, 5]

How does it work?

wll-interface works by effectively creating the following code, making calls to LibraryLink functions. It is done automatically depending on the type of arguments and the return value of function multiply.

EXTERN_C DLLEXPORT int wll_multiply(
    WolframLibraryData, mint argc, MArgument* args, MArgument res)
{
    double arg0 = MArgument_getReal(args[0]);
    int    arg1 = MArgument_getInteger(args[1]);
    double result = multiply(arg0, arg1);
    MArgument_setReal(res, result);
    return LIBRARY_NO_ERROR;
}