The presentation is confusing because of a mismatch between the headings/blurbs and what is being shown in the code examples.
The heading of the entire page is "the essence of computation" but I'm not shown why the code examples (which at a cursory glance look like a run-of-the-mill FP language) warrant that claim.
Then we read that there is "one operator", but that's clearly not visible from the examples. You have to read the comments in the playground to understand that things like definitions, lambdas, lists, etc. are syntactic sugar added on top of TC (which is fine, but it's just not transparent initially). In general, the distinction between TC (a formal calculus) and the programming language implemented here based on TC is not made clear enough.
The code examples themselves are fine (and there's some interesting things in there), but I stumbled over the "try to invert function" example. While the example itself is reasonably clear, it's not at all clear what that would mean in the general case - you clearly can't invert all functions (especially not non-injective ones). That should definitely be explained better.
The heading of the entire page is "the essence of computation" but I'm not shown why the code examples (which at a cursory glance look like a run-of-the-mill FP language) warrant that claim.
Then we read that there is "one operator", but that's clearly not visible from the examples. You have to read the comments in the playground to understand that things like definitions, lambdas, lists, etc. are syntactic sugar added on top of TC (which is fine, but it's just not transparent initially). In general, the distinction between TC (a formal calculus) and the programming language implemented here based on TC is not made clear enough.
The code examples themselves are fine (and there's some interesting things in there), but I stumbled over the "try to invert function" example. While the example itself is reasonably clear, it's not at all clear what that would mean in the general case - you clearly can't invert all functions (especially not non-injective ones). That should definitely be explained better.