What is extempore?

Extempore is a systems programming language designed to support the programming of real-time systems in real-time. Extempore promotes human orchestration as a meta model of real-time man-machine interaction in an increasingly distributed and environmentally aware computing context.

Extempore is designed to support a style of programming dubbed 'cyberphysical' programming. Cyberphysical programming supports the notion of a human programmer operating as an active agent in a real-time distributed network of environmentally aware systems. The programmer interacts with the distributed real-time system procedurally by modifying code on-the-fly. In order to achieve this level of on-the-fly interaction Extempore is designed from the ground up to support code hot-swapping across a distributed heterogeneous network, compiler as service, real-time task scheduling and a first class semantics for time.

Extempore is designed to mix the high-level expressiveness of Lisp with the low-level expressiveness of C. Extempore is a statically typed, type-inferencing language with strong temporal semantics and a flexible concurrency architecture in a completely hot-swappable runtime environment. Extempore makes extensive use of the LLVM project to provide back-end code generation across a variety of architectures.

For more detail on what the Extempore project is all about, see the Extempore philosophy.

To see Extempore in action, check out these videos:

• interactive, distributed, physics simulation
• graphics demo
• general introduction
• a more technical intro

Documentation

More Extempore documentation can be found at http://benswift.me/extempore-docs/index.html

You can also join the Extempore community:

• Extempore google group
• Extempore mailing list

Installation on Linux & OS X

More detailed instructions can be found here

Building Extempore depends on the following libraries (you can probably get them through your favourite package manager).

• LLVM 3.2
• pthread
• pcre (Perl-compatible Regular Expressions)
• portaudio v1.9
• mesa GL (Linux only)

LLVM must be version 3.2 and needs to be built from source, because a small patch to LLParser.cpp (an LLVM source file) is required. You can get the LLVM v3.2 source from http://llvm.org/releases/download.html#3.2.

The patch file llparser.patch is supplied in the extempore/extras directory.

$ cd /path/to/llvm/lib/AsmParser
$ patch < /path/to/extempore/extras/llparser.patch

After patching, building LLVM is the usual ./configure; make; make install process, with the addition of a --prefix location specifying where everything will be installed into (such as a Build directory)

$ cd /path/to/llvm
$ mkdir Build
$ ./configure --prefix=/path/to/llvm/Build --enable-optimized
$ make -j4
$ make install

Once all of the libraries required for your platform (see list above) are installed, you can compile Extempore. First, point to your LLVM build directory with the shell variable EXT_LLVM_DIR.

$ export EXT_LLVM_DIR=/path/to/llvm/Build

Then you can build extempore using the all.bash shell script

$ ./all.bash

Voila... you should be done.

Installation on Windows 7

More detailed instructions can be found here

Extempore has thus far only been tested on Windows 7 64-bit, but if you can get it to build/run on other flavours of Windows then do let us know and we'll update these instructions. Also, if anyone wants to improve and streamline the Windows build process, then patches are welcome :)

On Windows 7, building Extempore requires the following libraries:

• LLVM 3.2
• pcre
• boost v1.47
• portaudio v1.9

Boost is mandatory on Windows, and you will need to build pcre, boost, portaudio and LLVM 3.2 yourself.

To do this, the source directories will need to be on the 'include path':

• llvm-3.2
• boost_1_47_0
• pcre-8.12
• portaudio

Similarly, you'll need to make some directories for the results of building the above libs

• my_llvm_build - use cmake to create then build using msvc
• my_boost_build - use bjam (see below --build-dir=my_boost_build)
• my_pcre_build - use cmake to create then build using msvc
• build portaudio using provided msvc project (portaudio/build/msvc/portaudio.sln)

LLVM must be version 3.2 and needs to be built from source, because a small patch to LLParser.cpp (an LLVM source file) is required. The patch file llparser.patch is supplied in the extempore/extras directory. You can get the LLVM source from http://www.llvm.org/

The extempore/extras/llparser.patch file contains the patch, but because GNU patch isn't installed by default on Windows patching this file isn't quite as simple as it was on Linux/OS X. To apply the patch on Windows there are a couple of options:

1. Get GNU patch in the form of patch.exe (maybe also check out this advice) and apply the patch in the same way as is described above in the 'Linux & OS X section'
2. Apply the patch manually - look at the file lib/AsmParser/LLparser.cpp in the LLVM source directory and the patch file in a text editor and make the required changes by hand. A bit cumbersome, but you only have to do it to compile extempore.

The extempore build process is pretty simple once you've built the libraries. The extempore directory expects to find itself in the same directory as all of the directories mentioned above, although you can change all of this by manually editing extempore/msvc/extempore.vcxproj.

If you have now built everything successfully you should be able to build extempore from the command line.

First set the shell's vc/build environment vars

> cd extempore\msvc
> ms_build_vars.bat

You'll need a full version of Visual Studio to get the 64bit compiler (cl.exe). Then you can build Extempore:

> cd extempore
> all.bat

Additional Windows Build Notes

• Use CMake to build pcre (my_pcre_build)
• Use CMake to Build LLVM (choose 64bit option - my_llvm_build)
• Make sure that Debug build mode has _ITERATOR_DEBUG_LEVEL=2 set for both
• CMAKE_CXX_FLAGS_DEBUG and CMAKE_C_FLAGS_DEBUG (click advanced checkbox in cmake gui)
• Make sure portaudio msvc general project settings are set to static lib
• boost command line for bjam is:

bjam --build-dir=<dir> toolset=msvc link=static address-model=64 variant=release --build-type=complete stage

• extempore msvs project settings needs PCRE_STATIC to be defined if you want to build against pcre static libs
• extempore msvs project needs EXT_BOOST to be defined
• pcreposix.lib needs to come before pcre.lib in link list
• You might need to add PA_WDMKS_NO_KSGUID_LIB if you compiling portaudio for 64bit.

Running Extempore

You don't need to do anything special to run extempore, it'll just run in any terminal (or command prompt on Windows).

$ ./extempore

The running extempore process acts as a server, and you send extempore code to the server for evaluation (by default on port 7099).Once you've started extempore you can connect using either telnet, Emacs, vim, sublime text, or whatever you like. The Emacs support is probably the most mature at the moment, but patches are welcome for other editors.

There are some optional command line options that you may want to use you can get a list by running ./extempore --help

For more detail, see this post on interacting with the Exempore compiler.

Telnet

If using telnet the default extempore port to connect to is 7099.

Emacs

Add this code to your .emacs

(autoload 'extempore-mode "/path/to/extempore/extras/extempore.el" "" t)
(add-to-list 'auto-mode-alist '("\\.xtm$" . extempore-mode))

To start an Extempore session:

1. Open a shell buffer (M-x shell), cd to the extempore directory and start it up with ./extempore
2. Switch to an .xtm file (e.g. from the examples subdirectory) or create a new one
3. You're away. C-x C-x will eval an expression and C-x C-r will eval the region

Version note: the Emacs major mode (extempore-mode) only works with Emacs 24 because it inherits from prog-mode. If for some reason you have to stick on Emacs 23, you can use the Extempore minor mode (extras/extempore-minor.el).

Windows note: if you choose to use emacs on windows (recommended) and run extempore in a shell or eshell then you should set --term ansi as an option when starting extempore.

Sublime Text

You'll need the ST2 Extempore plugin, which provides syntax highlighting and some commands for connecting to and working with a running Extempore process. To install the plugin, download the plugin files (or clone the repo) and unzip them into your ST2 packages directory.

Then, to to start hacking on Extempore code in ST2:

1. open up your favourite shell (e.g. Terminal.app on OS X or cmd.exe on Windows)
2. start Extempore: cd into your Extempore directory and run ./extempore
3. in ST2, open an Extempore file (the Extempore plugin should be loaded automatically when ST2 sees the .xtm file extension)
4. connect to the running Extempore process (ctrl+x, ctrl+y)

Then, to evaluate Extempore code, highlight the code you want to evaluate and hit extempore_evaluate (which by default is mapped to ctrl+x ctrl+x).

To restart the Extempore process, just ctrl+c in the shell where extempore is running to kill it, then start it up again.

Vim

If you want to use (g)vim, see the instructions found in extras/extempore.vim.

Licence

Copyright (c) 2011-2013, Andrew Sorensen

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

Neither the name of the authors nor other contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.