This repository contains Prolog code for a simple question-answering assistant. The top-level module is prolexa.pl, which can either be run in the command line or with speech input and output through the alexa developer console.

The heavy lifting is done in prolexa_grammar.pl, which defines DCG rules for sentences (that are added to the knowledge base if they don't already follow), questions (that are answered if possible), and commands (e.g., explain why something follows); and prolexa_engine.pl, which implements reasoning by means of meta-interpreters.

Also included are nl_shell.pl, which is taken verbatim from Chapter 7 of Simply Logical, and an extended version nl_shell2.pl, which formed the basis for the prolexa code.

The code has been tested with SWI Prolog versions 7.6.0 and 8.0.3.

Command-line interface

% swipl prolexa.pl
Welcome to SWI-Prolog (threaded, 64 bits, version 8.0.3)
SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.
Please run ?- license. for legal details.

For online help and background, visit http://www.swi-prolog.org
For built-in help, use ?- help(Topic). or ?- apropos(Word).

?- prolexa_cli.
prolexa> "Tell me everything you know".
*** utterance(Tell me everything you know)
*** goal(all_rules(_7210))
*** answer(every human is mortal. peter is human)
every human is mortal. peter is human
prolexa> "Peter is mortal".
*** utterance(Peter is mortal)
*** rule([(mortal(peter):-true)])
*** answer(I already knew that Peter is mortal)
I already knew that Peter is mortal
prolexa> "Explain why Peter is mortal".
*** utterance(Explain why Peter is mortal)
*** goal(explain_question(mortal(peter),_8846,_8834))
*** answer(peter is human; every human is mortal; therefore peter is mortal)
peter is human; every human is mortal; therefore peter is mortal

Amazon Alexa and Prolog integration

Follow the steps below if you want to use the Amazon Alexa speech to text and text to speech facilities. This requires an HTTP interface that is exposed to the web, for which we use Heroku.

Generating intent json for Alexa

swipl -g "mk_prolexa_intents, halt." prolexa.pl

The intents are found in prolexa_intents.json. You can copy and paste the contents of this file while building your skill on the alexa developer console.

Localhost workflow (Docker)

To build:

docker build . -t prolexa

To run:

docker run -it -p 4000:4000 prolexa

To test the server:

curl -v POST http://localhost:4000/prolexa -d @testjson --header "Content-Type: application/json"

Heroku workflow

Initial setup

Prerequisites:

• Docker app running in the background
• Installed Heroku CLI (brew install heroku/brew/heroku)

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To see the status of your Heroku webapp use

heroku logs

in the prolexa directory.

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1. Clone this repository

   git clone git@github.com:So-Cool/prolexa.git
   cd prolexa
   

2. Login to Heroku

   heroku login
   

3. Add Heroku remote

   heroku git:remote -a prolexa
   

Development workflow

1. Before you start open your local copy of Prolexa and login to Heroku

   cd prolexa
   heroku container:login
   

2. Change local files to your liking

3. Once you're done push them to Heroku

   heroku container:push web
   heroku container:release web
   

4. Test your skill and repeat steps 2. and 3. if necessary

5. Once you're done commit all the changes and push them to GitHub

   git commit -am "My commit message"
   git push origin master