Foreign Exchange at Low, Low Rates

We present a novel yet simple foreign function interface, designedfor web-targeting Haskell dialects but also applicable to a widerrange of high-level target languages. The interface automates marshalling,eliminates boilerplate code, allows increased sanity checkingof external data, allows the import of functions as well as arbitraryexpressions of JavaScript code, and is implementable as aplain Haskell ’98 library without any modification to the Haskellcompiler or environment.We give an implementation of this interface for the JavaScripttargetingHaste compiler, and show how the basic implementationcan be further optimized with minimal effort to perform on par withHaskell’s vanilla foreign function interface, as well as extended tosupport automatic marshalling of higher-order functions and automaticmarshalling of host language exceptions. We also discusshow the interface may be extended beyond the web domain andimplemented across a larger range of host environments and targetlanguages