Arrays of objects

This paper discusses key design decisions faced by a language design team while adding Object Oriented language features to Dyalog, a modern dialect of APL. Although classes and interfaces are first-class language elements in the new language, and arrays can both contain and be contained by objects, arrays are not objects. The use of object oriented features is optional, and users can elect to remain entirely in the functional and array paradigms of traditional APL. The choice of arrays as a "higher" level of organization allows APL's elegant notation for array manipulation to extend smoothly to arrays of objects.