Comment by zozbot234

It is accessible if you know a few bits of syntax, such as → being right-associative so τ1 → τ2 → τ3 means τ1 → (τ2 → τ3). And others such as "f: X → Y declares f as a function from X's to Y's." which you can find in any math textbook. The point of using such a terse notation rather than faffing around with Callable[…] is to make it possible to work with larger examples without getting bogged down in the verbiage. It's why we use symbols to solve equations in K-12 math.