Trellis-Owl

Trellis/Owl, or simply Owl,^[a] is a defunct object-oriented^[2] programming language created by Digital Equipment Corporation.^[3] It was part of a programming environment, Trellis. It ran on the OpenVMS operating system.

Trellis/Owl differed from contemporary languages in several ways. For one, it did not use dot notation for method calls on objects, and used a traditional functional style instead, which they referred to as operations. Operations were supported by the concept of a controlling object, the first parameter in the function call, which indicated which class was being referred to. Whereas most OO languages of the era might have a myStringVariableToPrint.print() method, in Trellis/Owl this would be print(myStringVariableToPrint), and the print method of the class String would be called based on a string being the first parameter.^[4] Trellis/Owl also supported properties, which they referred to as components.^[5] Trellis/Owl also included a system allowing the easy creation of iterators, using the yields keyword to replace returns in the definition of an operation. yields indicates the operator will return a series of values instead of one.^[6]