# Applying KeY to programs with generics¶

## Support¶

At present, you cannot prove properties about Java programs with generics in KeY. However, a routine is provided to remove genericity from Java programs, reducing them to equivalent Java2 programs without generics. This routine is currently not invoked automatically when source code is loaded, but needs to be run on the sources beforehand.

## Removing Generics from a Program¶

The removing generics functionality is located in the executable created by

./gradlew shadowJar


It can be invoked from the key/key.ui/build/libs folder:

java -cp key-2.7-exe.jar de.uka.ilkd.key.util.removegenerics.Main


If you provide no parameters, a usage information is printed.

If you want to remove generics in the .java-files in directory DIR and write the results to directory OUT, call:

java -cp key-2.7-exe.jar de.uka.ilkd.key.util.removegenerics.Main -d OUT DIR


It may be that you need to provide additional classpath information which can be provided using another -cp argument (on the commandline behind the Main classname).

The transformed classes can then be loaded into KeY.

## Technical Details¶

The reason why generics are currently not implemented in KeY lie in the type system of KeY: There, every Java class is represented by a type of its own. To talk about "some" type, "type variables" or "type placeholders" would be needed.

Alternatively, the type parameter information could be formalised as predicates in the logic (typeof(expr) = java.lang.String). But this would imply a hybrid situation with some type information available in the type system and some in semantic predicates. A reasonable, yet drastic step would be to transfer typing information to the semantic level entirely.