SWI-Prolog ported to WebAssembly

This repository contains instructions to compile a Prolog implementation SWI-Prolog (http://swi-prolog.org) to WebAssembly.

Compilation

These compilation instructions assume Linux-based host machine. The resulting WebAssembly binary is platform-independent.

Note: This build will NOT work on a Raspberry PI due to the non-64-bit architecture.

Preparation

You need to download the Emscripten compiler. Follow the instruction on its homepage.

this build will place certain source files in your $HOME.

########################################################

# Install Dependencies 

apt update
apt upgrade

apt-get install -y \
	apt-utils \
	build-essential cmake pkg-config \
	git \
	ncurses-dev libreadline-dev libedit-dev \
	libgoogle-perftools-dev \
	libunwind-dev \
	libgmp-dev \
	libssl-dev \
	unixodbc-dev \
	zlib1g-dev libarchive-dev \
	libossp-uuid-dev \
	libxext-dev libice-dev libjpeg-dev libxinerama-dev libxft-dev \
	libxpm-dev libxt-dev \
	libdb-dev \
	libpcre3-dev \
	libyaml-dev \
	python3

########################################################

# Build ZLib   
wget https://zlib.net/zlib-1.2.11.tar.gz -O "$HOME/zlib-1.2.11.tar.gz"
tar -xf "$HOME/zlib-1.2.11.tar.gz" -C "$HOME"
cd "$HOME/zlib-1.2.11"
emconfigure ./configure
emmake make

########################################################

# Build Emscripten   
cd $HOME
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install latest
./emsdk activate latest

# After the successful installation load the Emscripten
#environment into the current terminal session (adjust path):
source ./emsdk_env.sh

########################################################

# Build SWIPL       
cd $HOME
git clone https://github.com/SWI-Prolog/swipl-devel.git
cd swipl-devel
git submodule update --init

## 'Development' Build...
mkdir build
cd build
cmake -DSWIPL_PACKAGES_JAVA=OFF ..
make
make install

##  'WASM' 'Development' Build...
cd $HOME/swipl-devel
mkdir build.wasm
cd build.wasm
cmake -DCMAKE_TOOLCHAIN_FILE=$HOME/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake \
      -DCMAKE_BUILD_TYPE=Release \
		  -DZLIB_LIBRARY=$HOME/zlib-1.2.11/libz.a \
		  -DZLIB_INCLUDE_DIR=$HOME/zlib-1.2.11 \
      -DMULTI_THREADED=OFF \
      -DUSE_SIGNALS=OFF \
      -DUSE_GMP=OFF \
      -DBUILD_SWIPL_LD=OFF \
      -DSWIPL_PACKAGES=OFF \
      -DINSTALL_DOCUMENTATION=OFF \
      -DSWIPL_NATIVE_FRIEND=build \
      -G "Unix Makefiles" ..
      
emmake make


########################################################

# Move WASM Source Files to Build (to allow friend-build dependencies)
#


# ... and all of the other WASMs?

Usage

Please see "Foreign Language Interface" (FLI) in the SWI-Prolog manual. A very limited set of function findings into JavaScript can be seen in the demo. The bindings use cwrap from Emscripten.

General workflow:

Set up a stub Module object with noInitialRun: true and other options.
Set up FLI bindings in Module.onRuntimeInitialized.
Use the bindings to call PL_initialise.
Set up the location for standard library.
Use the FS API to write code files into the virtual filesystem.
Load the code files from SWI-Prolog side using consult/1 or a similar way.
Interact with SWI-Prolog through its FLI.

Demo

See example/index.html as a simple example. It can be found online at http://demos.rlaanemets.com/swi-prolog-wasm/example/. The commented code inside the demo provides the documentation.

To test it out locally, you need to serve the files through an HTTP server.

TODO

Provide full set of bindings?
A way to call JavaScript from SWI-Prolog.
Compile and add useful packages.
Provide a mechanism to load packs?
Easier way to turn Prolog terms into JS objects?
See where WebAssembly goes and what interfaces could be added (direct DOM access?).

License

SWI-Prolog is covered with the Simplified BSD license. See http://www.swi-prolog.org/license.html

zlib is covered with the zlib license. See https://zlib.net/zlib_license.html

jacobfriedman / swipl-wasm