The art of knitting lace is an intricate process; it takes great skill with knitting and the ability to keep track of complex knitting instructions. One day, my wife Sophie was knitting a particularly complex pattern, and she complained about not being able to keep track of how many stitches she should have for a particular row or how many should be left in the next row. Enter the programmer! I’ve been throwing together little utilities for myself for ages. Sometimes I want to calculate some value that would take too long by hand; sometimes I want to sort a list in some particular way. Other times I have trouble deciding what to have for dinner, so I’ll write up a list of options and then pop in a random number to pick from it. I have one such script from ages ago that I used regularly when living in Montreal. It was clear to me that Sophie needed software to handle her problem. With instructions spanning up to a hundred stitches, it’s the sort of thing that’s hard to keep track of...