Passages

Donald E. Knuth's Literate Programming is only the second Knuth book I have reviewed here, but his sensibility and example have informed many Passages columns, including those on Brooks' The Mythical Man- Month and Martin Gardner's recreational mathematics columns. Literate Programming , in the title, explains why that is so. The central idea of this column series is that software engineering is, to a large extent, a literary endeavor: that we write programs, yes, for computers to execute, but also for human beings to read and understand. The first reason we write such programs specifically for human beings is common between conventional literature and computer programs as literature: the books, poems, short stories, and, yes, computer systems, of the future are composed by reading and understanding and reworking the books, poems, short stories, and, yes, computer systems of the past. There are no illiterate authors; books are made, famously, of other books. Countess Lovelace and Alan Turing, by necessity, wrote programs to a large extent de novo, but their actual code was not the most important aspect of their work; such invention is not the common practice of the field.