egel

The Egel Language

Egel is an untyped concurrent functional scripting language based on eager combinator rewriting with a concise but remarkably powerful syntax.

Installation

This interpreter is being developed on Linux/MacOS/BSD and uses icu4c for Unicode support, fmt for formatting, ffi as a foreign function interface, and GNU lightning as a ahead-of-time backend.

The interpreter can be compiled with a current C++ compiler and employs cmake to build. In general, you will need root access to build egel.

There are roughly two manners in which operating systems and package managers provide C++ libraries.

1. The open source model (various Unixes and BSDs) where C++ libraries are compiled and dissimated by the operating system distributor. Use your package manager to install libicu, libffi, fmt, and GNU lightning.

   Warning: exceptionally, Ubuntu/Debian doesn't ship with GNU Lightning. You are supposed to compile and install that package prior to compiling the interpreter.

2. The vendor based model (MacOS and Windows) where C++ libraries are usually not provided since they are brittle to link against, and where one usually compiles these libraries from scratch and statically links them in or distributes them with the application. Links to the vendors are provided as git submodules in the vendor directory and, you're on your own here, you'll need to download and compile those libraries. There's a separate README.md in the vendor directory that should help somewhat.

CMake files are provided for both models, select the one you want to use and rename either to CMakeLists.txt.

A static build cmake script based of the vendor model is also provided.

After that the interpreter is made with cmake in the standard manner. Run the following commands on a Linux system.

    mkdir build
    cd build
    cmake ..
    make

note: for older GCC you sometimes need to uncomment the stdc++fs rule.

That should give you an interpreter named egel and a number of dynamically loadable Egel object files in the build directory.

For a system-wide install run make install after a build as root.

(MacOS dyld doesn't look in /usr/local/lib anymore, set the path.)

On some systems the EGEL_PATH environment variable needs to be set. See the man page for further information on that.

If you don't want to do that, please note that you only need the interpreter named egel and the prelude in the include directory for simple tasks.

Cmake generated makefiles allow for a local install with the command:

    make DESTDIR=~ install

In this case Egel components will be installed into ~/usr/local directories and you might refer to those components by adding the following commands to your shell resource file, though the specific syntax may differ.

    export PATH=~/usr/local/bin:$PATH
    export EGEL_PATH=.:~/usr/local/lib/egel

Usage

There's a manual page you can consult, it should be installed, or read the following short introduction to the interpreter on the internet.

For a list of builtin combinators look here.

Also

The interpreter doesn't provide command line editing, you might want to wrap it with the command alias egel="rlwrap egel".

The interpreter allocates lots of short-lived objects. If you want a bit of extra speed, it might pay off to switch the allocator.

I use jemalloc on Linux by setting LD_PRELOAD=`jemalloc-config --libdir`/libjemalloc.so.`jemalloc-config --revision.