# Introduction¶

SCHeMe UnterstüTZung

schmutz is a library to declare Scheme bindings for C++ code using a simple embedded DSL. Think of it as Boost.Python or LuaBind but for Scheme. At the moment, it only works with the GNU Guile Scheme implementation, but multiple backend support is considered for the future.

This research project is part of a long-term vision helping interactive and concurrent C++ programs become easier to write. Support our vision by becoming a patron or buying a sponsorship package: juanpe@sinusoid.al

## Example¶

In the C++ world…

#include <scm/scm.hpp>
#include <numeric>

class counter {
std::size_t count_ = 0;
public:
std::size_t get() const { return count_; }
void tick() { ++count_; }
};

int fold_args(scm::val fn, scm::val fst, scm::args xs) {
return std::accumulate(xs.begin(), xs.end(), fst, fn);
}

extern "C" void init_module() {
scm::type<counter>("counter")
.constructor()
.define("get", &counter::get)
.define("tick!", &counter::tick);
scm::group()
.define("the-answer", [] { return 42; })
.define("fold-args", fold_args);
}


In the Scheme world…

(use-modules (example module)
(oop goops)
(rnrs base))

(let ((cnt (counter)))
(assert (is-a? cnt <counter>))
(counter-tick! cnt)
(counter-tick! cnt)
(counter-tick! cnt)
(assert (= 3 (counter-get cnt))))

(assert (= 6 (fold-args + 0 1 2 3)))


## Usage¶

This is a header only library. As long as you already have Guile installed, you can just copy the scm subfolder somewhere in your include path.

Otherwise, if you are using the Guix package manager you can just:

git clone https://github.com/arximboldi/schmutz
guix package -f schmutz/guix.scm -i


Or if you are using the Nix package manager you can just:

nix-env -if https://github.com/arximboldi/schmutz/archive/master.tar.gz


Alternatively, you can use CMake to install the library in your system once you have manually cloned the repository:

mkdir -p build && cd build
cmake .. && sudo make install


## Development¶

In order to develop the library, you will need to compile and run the examples, tests and benchmarks. These require some additional tools. The easiest way to install them is by using the Guix package manager or the Nix package manager. At the root of the repository just type:

guix environment -l guix.scm


Or alternatively:

nix-shell


This will download all required dependencies and create an isolated environment in which you can use these dependencies, without polluting your system.

Then you can proceed to generate a development project using CMake:

mkdir build && cd build
cmake ..


From then on, one may build and run all tests by doing:

make check


schmutz - Scheme Unterstüzung
Copyright (C) 2017 Juan Pedro Bolivar Puente

Boost Software License - Version 1.0 - August 17th, 2003

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