Any text that defines piecewise functions is going to use syntax similar to Knuth. It's much older than him or his text. Piecewise functions are not common in t

Any text that defines piecewise functions is going to use syntax similar to Knuth. It's much older than him or his text. Piecewise functions are not common in the normal math track though, because they're not continuous and differentiable, so they make the path to calculus more complex. In my experience, it is we programmers who care about syntax the most. Math folks seem to be happy if you can get the gist of something. Still, you're right, the semicolon/period thing is troubling for Erlang beginners, but that part of the syntax really does come from Prolog.