Crosscut

Yesterday, I started introducing the new syntax and evaluation model. It takes inspiration from functional languages, and limits functions to having exactly one input and one output value. That might seem too restrictive: some operations just have multiple inputs. Otherwise, how would you model something like addition or multiplication?

Functional languages like Haskell or the ML family, get around that by using currying. Consider something like + 1 2 (which is a syntax that neither of the aforementioned languages use for addition; but let's stick with it for this example). This isn't actually a single call taking two arguments; it's two function calls, taking one argument each!

The first call (or application, as the more math-minded functional languages call it) is + 1. It returns a new function, which takes a single argument and adds 1 to it. That new function is what receives the argument 2. I don't think this would work with postfix syntax though. So we need a different solution.