Exception Handlers as Extensible Cases

Abstract. Exceptions are an indispensable part of modern programming languages. They are, however, handled poorly, especially by higherorder languages such as Standard ML and Haskell: in both languages a well-typed program can unexpectedly fail due to an uncaught exception. In this paper, we propose a technique for type-safe exception handling. Our approach relies on representing exceptions as sums and assigning exception handlers polymorphic, extensible row types. Based on this representation, we describe an implicitly typed external language EL where well-typed programs do not raise any unhandled exceptions. EL relies on sums, extensible records, and polymorphism to represent exceptionhandling, and its type system is no more complicated than that for existing languages with polymorphic extensible records. EL is translated into an internal language IL that is a variant of System F extended with extensible records. The translation performs a CPS transformation to represent exception ha...

• Type: Conference
• Year: 2008
• Where: APLAS
• Authors: Matthias Blume, Umut A. Acar, Wonseok Chae
• Keywords: APLAS 2008, Exception Handlers, Extensible Records, Polymorphic Extensible Records, Programming Languages