More than a quarter of all computer programming jobs have vanished in the past two years, the worst downturn that industry has ever seen. Things are sufficiently abysmal that computer programming ranks among 10 hardest-hit occupations of 420-plus jobs for which we have data from the Bureau of Labor Statistics.Learning to code was supposed to save millions of would-have-been liberal arts majors. But today there are fewer programmers in the United States than at any point since 1980. That’s a 45-y...