Navigating through a series is not rocket science, but you have to get used to it. Follow along in the console, and, to really get it, draw some pictures, such as the ones we will show you.
Navigating and looping through a series
A step at a time – head, tail, index?, and next
The data word from the previous section is not only a name for the series—it is also a pointer to where we are in the series at a particular moment. You could call that position the current index, which is given by the index? function. Right after the series is created, we have index? data ;== 1 . Here is a diagram so you can quickly see what is going on:
Remember that in Red, an index starts from 1, not from 0, as in most other (C-based...