Chirp Blog

So, you want to define your own procedures and functions in Scratch? Build your own blocks (BYOB )?

You might as well try this new experimental prototype I have been developing over the last weeks. You can download and read through an overview (pdf), or download the whole application (including the overview) and start playing with it right away.

This prototype lets you build your own custom blocks in Scratch using the standard Scratch blocks, as well as other blocks you defined elsewhere. You can create your own command blocks (procedures) and reporter blocks (functions), both regular (”round”) and boolean (”diamond”). You can specify for each block to be atomic (run at the speed of a single block) or interleafed. Your custom blocks are defined for each sprite and can be shared among projects together with the sprite they were created for. Oh, and you can even use a block within itself (recursion).

This prototype is very, very, experimental, so be prepared to encounter lots of bugs. I’d be very interested in feedback about your experiences and insights.

Enjoy!

-Jens

update: Check out recent and ongoing BYOB-development (first class procedures etc.) at: byob.berkeley.edu