A package for handling units of measure in Lisp

Abstract

The ability to handle units of measure in a programming environment together with numerical quantities in scientific and engineering programs helps greatly in achieving computational safety as well as code and data readability. It allows for dimensional analysis, thus safeguarding against erroneous combination of values of different dimensionality, e.g. adding distances to masses, or against scaling errors, e.g. assigning distances measured in inch to variables supposed to hold centimeters. Associating values and variables with units of measure explicitly clarifies code and data and---given a clever compiler---allows for the above-mentioned dimensional analysis to be performed at compile time. If extended to input and output of user data, it might free the user from the burden to perform proper scaling himself when entering data conforming to program-defined units of measure. And it might allow for easy customization of output in order to present computational results to users familiar with different sets of units of measure, e.g. British and American use of units versus metric units.