LambdaDL – a λ-DL implementation in Perl 6 for the Software Languages Team and Institute for Web Science of the University of Koblenz-Landau

Build it:

./configure
make

Write some λ-DL code:

// influences.lambda
@share/music.rdf
map
    λ(artist:<:MusicArtist>).
        case artist of
            type <:MusicArtist> as a → a.<:influencedBy>
            default nil[<:MusicArtist>]
in
    query <:MusicArtist>

And run it:

./lambdadl influences.lambda

Re-implementation of λ-DL so that I understand how it works. See https://west.uni-koblenz.de/lambda-dl for a thorough explanation of the idea.

That page also provides the original prototype for the language. However, it's written in F♯ and interfaces with the Java reasoner by running an external process for every query. Due to the JVM's glacial startup time, it is rather slow.

This project uses Perl 6 instead and interfaces with the same Java reasoner via C. So despite Perl 6's own (as of now) glacial speed, it's much faster at running those queries. It is also able to keep direct references to the Java objects around, rather than having to juggle string IDs around.

There's some changes to the original language:

• Identifiers follow the same rules as Perl 6, so don't-panic is a valid variable or function name.

• cons a, b instead of cons a b to avoid visual ambiguity with function application.

• → is used instead of -> and ⁻ instead of ^-. It's 2017, things should support Unicode.

• map FUNC in LIST is supported because I couldn't be bothered to implement it in λ-DL itself.

It also doesn't implement a λ calculus interpreter, instead it just generates Perl 6 code and evaluates that.

• Perl 6 - https://rakudo.org/

• Java JDK 8, shouldn't matter if it's Oracle or OpenJDK

• A Unix-like environment (C compiler, sh, make, perl)

First run ./configure (which isn't autoconf). It should figure out where all your JNI headers and libraries are. If it can't, follow the instructions it gives to help it.

Then run make to build the Java and C libraries and run the tests.

Run ./lambdadl LAMBDADL-FILE to compile and evaluate a LambdaDL program. If you want a runnable script instead, use ./lambdadl --output=SCRIPT-FILE LAMBDADL-FILE instead.

• Precedence of = is too high and doesn't list associate.

• Type checking for nominal concepts might be wrong?

Apache License, Version 2