Operational semantics for multi-language programs

Abstract

Inter-language interoperability is big business, as the success of Microsoft's .NET and COM and Sun's JVM show. Programming language designers are designing programming languages that reflect that fact -SML#, Mondrian, and Scala, to name just a few examples, all treat interoperability with other languages as a central design feature. Still, current multi-language research tends not to focus on the semantics of interoperation features, but only on how to implement them efficiently. In this paper, we take first steps toward higher-level models of interoperating systems. Our technique abstracts away the low-level details of interoperability like garbage collection and representation coherence, and lets us focus on semantic properties like type-safety and observable equivalence.Beyond giving simple expressive models that are natural compositions of single-language models, our studies have uncovered several interesting facts about interoperability. For example, higherorder contracts naturally emerge as the glue to ensure that interoperating languages respect each other's type systems. While we present our results in an abstract setting, they shed light on real multi-language systems and tools such as the JNI, SWIG, and Haskell's stable pointers.

Reconciling method overloading and dynamically typed scripting languages

“…Type soundness of the lump embedding has been demonstrated [16]. To conserve space, we do not demonstrate the type soundness of JAVALITE, which does not present any major issue.…”

“…We then tie these models by extending them with the lump embedding, a technique proposed by Matthews and Findler [16]. This technique is used to represent JSmall values in Java and the other way around without allowing methods to be called.…”

“…The lump embedding is a simple method for giving operational semantics to multi-language systems [16]. It has been designed to be expressive enough to support a wide variety of embedding strategies.…”

Checking type safety of foreign function calls

“…Their focus is on ensuring that code fragments in the various languages have access to necessary resources while preserving the languages' semantics, which differs from our goal of checking types and GC properties in FFIs. Matthews and Findler [2007] study the semantics of mixing the typed and untyped lambda calculus to better reason about their interaction. They focus on high-level properties such as ensuring soundness of the typed language in the presence of foreign values, while our focus is on detecting errors in low-level glue code.…”

Reasoning About Multi-Lingual Exception Handling Using RIPLS

“…Like PolySPIN, Exu and JExu, these all lack formal underpinnings and are therefore subject to similar shortcomings. The only previous research on formal foundations for multi-lingual programming of which we are aware is that of Trifonov and Shao [14], Sullivan et al [13], and Matthews and Findler [10]. We have emulated the approach used in the first of these, namely describing a common formal language into which surface languages are translated in order that the interoperability issues can be explored.…”