LiquidJava - Extending Java with Refinement Types

Welcome to LiquidJava!

LiquidJava is an additional typechecker for Java that supports refinement types.

Simple example

@Refined("a > 0")
int a = 3; // okay
a = -8; // type error!

More information

• VSCode plugin for LiquidJava
• Examples of LiquidJava
• LiquidJava Specification of Java StdLib
• Formalization of LiquidJava

Setup the project

1. Clone the repository;
2. Open Eclipse and do Ìmport...\ Existing Maven Project selecting the folder liquidjava-umbrella and waiting for the build process to finish (bottom right update bar)
3. Select the liquidjava-umbrella folder, right click it and select Run as...\Maven install...
4. Select liquidjava-verifier, on right-click, go to Build Path\Link Source... and browse for liquidjava-verifier\target\generated-sources\antlr4 and select Finish

Run verification

In a specific project

Run the file liquidjava-verifier\api\CommandLineLaucher with the path to the target project for verification. If there are no arguments given, the application verifies the project on the path liquidjava-example\src\main\java.

JUnit tests

Inside the folder liquidjava-verifier\api\tests are three classes that test several examples available at liquidjava-example\src\test\java. To run the JUnit tests in one of the files, select it, right-click it and Run as...\JUnit tests. To run the all test suit, select the package tests (liquidjava-verifier\api\tests), right-click it, and do Run as...\JUnit tests. Make sure to run these tests after making changes in the verification code.

Project structure

• liquidjava-api: inlcudes the annotations that can be introduced in the Java programs to add the refinements
• liquidjava-examples: includes a main folder with the current example that the verifier is testing; and inlcudes the classes for the tests
• liquidjava-verifier: has the project for verification of the classes
  • api: classes that test the verifier. Includes the CommandLineLauncher that runs the verification on a given class or on the main folder of liquidjava-examples if no argument is given. This package includes the JUnit tests to verify if the examples in liquidjava-example/tests are correctly verified.
  • ast: represents the abstract syntax tree of the refinement's language.
  • errors: package for reporting the errors.
  • processor: package that handles the type checking.
  • rj_language: handles the processing of the strings with refinements.
  • smt: package that handles the translation to the smt solver and the processing of the results the smt solver produces.
  • utils: includes useful methods for all the previous packages.