This directory contains the source code of the L₃ compiler, written in Scala. All interactions with the compiler should be done through sbt, a Scala build tool.

Sbt can either be run in interactive mode, by simply typing sbt and then entering commands at the prompt, or in batch mode. The following sections use batch mode for illustration, but in practice interactive mode is often to be preferred as it avoids repeated startup of sbt itself.

Compiling

To compile the compiler, use the compile command:

$ sbt compile

(the dollar sign $ represents the shell prompt and should not be typed).

Testing

To test the compiler (and compile it beforehand, if necessary), use the test command:

$ sbt test

Running

To run the compiler (and compile it beforehand, if necessary), use the run command, followed by arguments for the compiler, e.g.:

$ sbt 'run ../library/lib.l3m ../examples/queens.l3'

The compiler accepts a list of files to compile as arguments. These files can have one of the following extensions:

.l3: A normal source file, containing L₃ code.
.l3m: A module file, containing a list of other files, which must also be either source files (with a .l3 extension) or other module files (with a .l3m extension).

Modules are expanded recursively, until only .l3 files remain. Then, duplicate file names are removed, with only the first occurrence kept. Finally, this list of files is fed to the compiler.

As an example, assume that the file lib.l3m references characters.l3m and integers.l3m, and that characters.l3m references characters.l3 while integers.l3m references both characters.l3m and integers.l3. Then, a command line consisting of lib.l3m and helloworld.l3 is expanded as follows:

lib.l3m helloworld.l3 (original command line),
characters.l3m integers.l3m helloworld.l3 (expansion of lib.l3m),
characters.l3 characters.l3m integers.l3 helloworld.l3 (expansion of characters.l3m and integers.l3m),
characters.l3 characters.l3 integers.l3 helloworld.l3 (expansion of the second characters.l3m),
characters.l3 integers.l3 helloworld.l3 (removal of duplicates).