And that's algebra. (x:xs) cuts any string but an empty string  into first character and the rest.
reverse returns an empty string given an empty string, but otherwise (line 2) concatenates the first character to the end of a reversed string.
Yes, a recursive definition.
Some kids get really good at concatenating (++) i.e. their arithmetic is really fine.
But they're not good at writing functions.
The concatenate-only crowd are quite employable and are said to have "business intelligence".
The function writers are said to "know algebra" and will be given further training in mathematics.
Note: [ ] is an empty list and an empty string because a string is just a list of characters. (Yes, this is Haskell again, another math notation, runs on machines).
On Sat, Nov 3, 2012 at 12:25 AM, Jonathan Crabtree <firstname.lastname@example.org> wrote: > The Greeks were ok at geometry yet bad at arithmetic. I made my own times table the way Euclid, Pythagorus Nicomachus learned their's and it's very hard to learn. > > My guess is more people say the Indians via the Arabs gave us the foundation of modern math.