logica 1.1a2

Logica language.

Logica: language of Big Data

Logica is an open source logic programming language for data manipulation. Logica is a successor to Yedalog, a language created at Google earlier.

Why?

Logica is for engineers, data scientists and other specialists who want to use logic programming syntax when writing queries and pipelines to run on BigQuery.

Logica compiles to StandardSQL and gives you access to the power of BigQuery engine with the convenience of logic programming syntax. This is useful because BigQuery is magnitudes more powerful than state of the art native logic programming engines.

We encourage you to try Logica, especially if

• you already use logic programming and need more computational power, or
• you use SQL, but feel unsatisfied about its readability, or
• you want to learn logic programming and apply it to processing of Big Data.

In the future we plan to support more SQL dialects and engines.

I have not heard of logic programming. What is it?

Logic programming is a declarative programming paradigm where the program is written as a set of logical statements.

Logic programming was developed in academia from the late 60s. Prolog and Datalog are the most prominent examples of logic programming languages. Logica is a language of the Datalog family.

Datalog and relational databases start from the same idea: think of data as relations and think of data manipulation as a sequence of operations over these relations. But Datalog and SQL differ in how these operations are described. Datalog is inspired by the mathematical syntax of the first order propositional logic and SQL follows the syntax of natural language.

SQL was based on the natural language to give access to databases to the people without formal training in computer programming or mathematics. This convenience may become costly when the logic that you want to express is non trivial. There are many examples of hard-to-read SQL queries that correspond to simple logic programs.

How does Logica work?

Logica compiles the logic program into a SQL expression, so it can be executed on BigQuery, the state of the art SQL engine.

Among database theoreticians Datalog and SQL are known to be equivalent. And indeed the conversion from Datalog to SQL and back is often straightforward. However there are a few nuances, for example how to treat disjunction and negation. In Logica we tried to make choices that make understanding of the resulting SQL structure as easy as possible, thus empowering user to write programs that are executed efficiently.

How to learn?

Learn basics of Logica by reading through tutorial located at tutorial folder. See examples of using Logica in examples folder. Tutrial and examples show how to access Logica from CoLab.

Why is it called Logica?

Logica stands for Logic with aggregation.

Installation

To be written.

Contact

To be written.

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Unless otherwise noted, the Logica source files are distributed under the Apache 2.0 license found in the LICENSE file.

This is not an officially supported Google product.