In 1994, in my second year of junior high school in Japan, a computer class
sat me in front of a Fujitsu FM R-50 running LogoWriter 2. There was a turtle
on the screen, and it left a line behind it wherever it walked. I got carried
away, my classmates crowded around the machine, and that was the first time I
ever succeeded at programming. It's the reason I write software for a living.

Seymour Papert, who designed Logo in 1967, died on 31 July 2016. That week I
started building a turtle graphics engine in Swift, so a kid could have on an
iPad what I'd had on that FM R-50.

Here's the part I actually care about. A boarding school in Ontario wrote to
say they were teaching with that engine, and their course ran in a particular
order: blocks first, then text, then each student plotted a shape of their own
on a pen plotter. That order is the design of this app. A child snaps blocks
together, and the pane right next to them shows the very same program as real,
syntax-colored Swift, ready to copy out. Blocks and code aren't two things here
— they're one program in two notations. The app is built for the day a child
outgrows it.

The rest: repeat, if, and boxes; dice in any number *or color* slot, so the
same program draws a different picture every run; and blocks you name yourself
— which can call themselves, so nine blocks on one screen draw a fractal tree.
Playback highlights the block being drawn, so it's never a mystery which block
made which line. Drawings are ordinary documents that show their own picture as
their icon; export SVG or PNG. iPad and Mac to build, Vision Pro to put the
finished drawing on your table.

No accounts, no ads, no analytics — there is no networking code anywhere in the
app at all. Free, and MIT on GitHub.

I'd love to hear what your kids draw with it.

Tortoise Blocks

Block coding for kids that grows up into Swift

Block coding for kids that grows up into Swift