Pallene

Pallene is a statically typed, ahead-of-time-compiled sister language to Lua, with a focus on performance. It is also a friendly fork of the Titan language.

Pallene is intended for writing performance sensitive code that interacts with Lua, a space that is currently filled by C modules and by LuaJIT. Compared to C, Pallene should offer better support for interacting with Lua data types, bypassing the unfriendly syntax and performance overhead of the Lua-C API. Compared to LuaJIT, Pallene aims to offer more predictable run-time performance.

Building the Pallene Compiler

In order to use this source distribution of the Pallene compiler, you need to install its Lua library dependencies and compile its run-time library.

Installing dependencies

The easiest way to install the dependencies for the Pallene compiler is through the LuaRocks package manager:

$ luarocks install --local --only-deps pallene-dev-1.rockspec

If you use the --local flag when installing packages from Luarocks, you may also need to configure the appropriate environment variables on your .bashrc. For further information, consult the Luarocks documentation.

If you want to use Pallene on Linux we also recommend installing the readline library:

$ sudo apt install libreadline-dev # for Ubuntu & Debian-based distros
$ sudo dnf install readline-devel  # for Fedora

Compiling the runtime libraries

Pallene must be run against a custom-built version of the Lua interpreter, as well as the Pallene runtime library. Both of these are written in C and must be compiled before the Pallene compiler can be used.

These two components can be built through the Makefile we provide. The command to be used depends on your operating system:

make linux-readline # for Linux
make macosx         # for MacOS

Usage

To compile a foo.pln file to a foo.so module call pallenec as follows.

Note: Your current working directory must be the root of this repository, due to Bug #16.

$ ./pallenec foo.pln

To run Pallene, you must currently use the bundled version of the Lua interpreter (again, see Bug #16).

$ ./lua/src/lua -l foo

For more compiler options, see ./pallenec --help

Developing Pallene

If you want to develop Pallene, it is helpful to know how to configure your editor to preserve our style standards, and to know how to run the test suite.

Configuring your editor

The easiest way to make sure you are indenting things correctly is to install the EditorConfig plugin in your favorite text editor.

This project uses 4 spaces for indentation, and tries to limit each line to at most 80 columns.

Using a linter.

We use Luacheck to lint our Lua source code. We recommend running it at least once before each pull-request or, even better, integrating it to your text editor. For instructions on how to install and use Luacheck, see our .luacheckrc file.

Running the test suite

We use Busted to run our test suite. It can be installed using LuaRocks:

$ luarocks install --local busted

To run the test suite, just run busted on the root directory of this repository:

$ busted                       # Run all tests
$ busted spec/parser_spec.lua  # Run just one of the test suite files

If you are debugging an unhandled exception in a test case, there are some helpful flags that you can pass to the busted command:

Flag	Effect
busted -v	Verbose output, including the stack trace
busted --no-k	Stop running tests after the first error
busted -o gtest	Changes the output formatting. This may be clearer if you are using print statements for debugging.

### Running the benchmarks suite

To run of the benchmarks in the benchmarks directory, tun the `benchmarks/run`
script from the root project directory:

```sh
./benchmarks/run benchmarks/sieve/pallene.pln

By default, the benchmark runner just outputs the running time, as measured by /usr/bin/time, but it also supports other measurements. For example, --mode=perf shows perf output and --mode=none shows the stdout produced by the benchmark, withot measuring anything.

./benchmarks/run benchmarks/sieve/pallene.pln --mode=none

To run benchmarks with LuaJIT, use the --lua option:

./benchmarks/run benchmarks/sieve/lua.lua --lua=luajit