A Java-based language with type-safe dynamic-code generation

In this thesis I describe an extension to the Java language that supports type-safe dynamic code generation. Dynamic code generation is a powerful technique for reducing execution time of pro-grams. It composes a portion of the execution code dynamically at runtime, generally mixing with some runtime-information. Since generated code holds runtime values such as number of an iteration or a condition of a branch as constants, it may run faster than statically-generated code. However, current dynamic code generators have several disadvantages. First, as most dynamic code generator are designed to generate native machine code, programs using dynamic code generation are not portable. Second, most systems have weakness on high-level language support for describing dynamic code fragment. Especially, safety of dynamic composition of code fragments is not sufficiently supported. Though it is partly solved in functional languages, it is not directly applicable to imperative settings. Many Java-based systems provide functions which generate code dynamically by directly manipulating bytecode. On those systems, safety of the generated code is the user’s re-sponsibility. Some systems allow the user to write a code fragment using high-level language constructs such as C and thus ensure type-safety within the fragment of code, but type-safety of more than one code fragments that are composed at runtime are not automatically guaranteed. To solve these problems, I define a strongly-typed language for dynamic code as an extension to Java language. This language gives precise types to dynamic code fragments. Our notion of types includes not only the types of code fragments of the base language, but also information of conditions that guarantee type safety of their composition. Type-checking these information confirms statically that result of composition of dynamic code fragments is still type-safe