Incomplete programs are ubiquitous in web repositories, evolving software projects and beyond; the ability to perform auto-completion on these incomplete programs provides several benefits, including: enabling static analysis tools to analyse incomplete programs; boosting developer productivity, and so on. However, earlier efforts to do so 1) are unable to work with incomplete programs containing parametrically polymorphic types and 2) may not respect the type safety of the incomplete program.

Therefore, in this extended abstract we present an algorithm that receives an incomplete Java program that may contain parametrically polymorphic types, and reconstructs its surrounding dependencies to form a well-typed program. As this algorithm does so in a type-safe manner, it can also cite the existence of non-trivial type errors in incomplete programs. Finally, we present results from a prototype implementation of this algorithm, JavaCIP.

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