Customer Reviews

A Programming Language.

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My current work involves high degrees of fine-grained computing parallelism. Looking for historical inspiration in how to represent such things, I wanted a reference on APL. That language famously (or infamously) swings around many-dimensioned arrays as easily as C handles integers, so has obvious applicability.

This book is not the reference I wanted. Instead, it's something even more fascinating, from a historical perspective. The first chapter develops APL's exotic (if not bizarre) notation and vast operator set, using reasonably rigorous math and quaint didactic style. The book is over 45 years old, as of this writing, and predates block-structured programming. As a result, its not-quite-flowchart diagrams embody "spaghetti code" at its finest.

I remember hearing many years ago that APL was originally a hardware description language (another of my current interests), and having a hard time believing that claim. This book's second chapter brings that to life. It addresses "microprogramming," a step above circuit design but below machine language programming that few in the current generation have even heard of - FYI, I've done microprogramming for the VAX 11/780 and a post-370 generation of IBM processors. The combination of APL's thousand-horsepower potential and strange flow-charts for handling bit-level operations in instruction decoding creates an Alice in Wonderland sense of large and small scale blended in some technological funhouse mirror.

Successive chapters describe data representation, sorting and searching, and other topics of pressing interest in the early 1960s. A modern reader might go cross-eyed trying to follow the microscopic scale of discussion, for example the huge mathematical buildup around packing data values into bit-fields - remember, back then a Kword of memory was huge, and word sizes hadn't settled into eight-bit bytes and their multiples. Sorting and searching, likewise, receive treatment that today's computer science students won't recognize. Even if you disregard the notational opacity, so many 1960s concerns have been forgotten that modern readers will struggle with the discussion just as they might struggle with Chaucer's English.

Imagine a kid playing in a grandparent's attic, and coming across a nineteenth century photo album. That's what a contemporary programmer feels reading this book. I didn't get the payload of practical information I came for. Instead, I found a charming and baffling relic from the history of my profession.

-- wiredweird

A Programming Language, by Kenneth E. Iverson, explores how programming language is a signifier for a whole host of mathematical algorithms and procedures. The book focuses on specific areas of application which serve as universal examples and are chosen to illustrate particular facets of the effort to design explicit and concise programming languages.