Quantity Checking through Unit of Measurement Libraries, Current Status and Future Directions

Unit errors are known to have caused some costly software engineering disasters, most notably the Mars Climate Orbiter back in 1999. As unit annotations are not mandatory for execution only dramatic events become newsworthy. Anecdotally however, there is evidence to suggest that these kinds of errors are recurrent and under-reported. There are an abundance of tools and most notably libraries to aid scientific developers manage unit definitions. In this paper we look in detail at how a number of prominent libraries in the most popular programming languages support units. We argue that even when these libraries are based on a sound design pattern, their implementation becomes too broad. Each library is distinct with varying features, lacking a core API, compromising both interoperability and thereby usage. We claim that further library or tool development is not needed to further adoption, but that a greater understanding of developers requirements is.