Snap! Reference Manual

Version 12.0

Snap! (formerly BYOB) is an extended reimplementation of Scratch (https://scratch.mit.edu) that allows you to Build Your Own Blocks. It also features first class lists, first class procedures, first class sprites, first class costumes, first class sounds, and first class continuations. These added capabilities make it suitable for a serious introduction to computer science for high school or college students.

In this manual we sometimes make reference to Scratch, e.g., to explain how some Snap! feature extends something familiar in Scratch. It’s very helpful to have some experience with Scratch before reading this manual, but not essential.

To run Snap!, open a browser window and visit https://snap.berkeley.edu/snap. The Snap! community web site at https://snap.berkeley.edu is covered briefly in The Snap! Community Site

The manual is roughly organized into a few sections.

• Chapters 1 to 11 cover the primary features for writing programs in Snap!. They are organized from introductory to advanced topics.

• Chapters 12 and 13 cover the user interface components of both the Snap! editor and the community site.

• The appendicies provide documentation for every block in Snap! block, as well as some of libraries provided.

Features of the Manual¶

You’ll find the table of contents on the left side of each page. At the bottom of each page, you’ll find previous and next links to navigate the manual in order. The right side of each page contains a list of all the sections in the current chapter. You can click on any of those to jump directly to that section.

A search function is included in the upper right hand corner.

PDF versions¶

We have three versions of the manual available for download as PDF files. The “Manual only” version includes all of the chapters and appendices, but does not include the sectoion labelled ‘Blocks Reference’. The “Blocks Reference” version includes only the section labelled ‘Blocks Reference’, which provides documentation for every block in Snap!, roughly one print page per block.

The “Manual + Blocks Reference” version includes both the manual and the blocks reference in a single PDF. (It is quite large, at around 500 pages, so it may take a while to download and open.) If you intend to print the manual, you may wish to print the “Manual only” version.

Manual only Blocks Reference Manual + Blocks Reference

Reference the Snap! Manual¶

If you’re writing a paper or book and want to reference the manual, please use the following citation:

@book{harvey_2025_17241865,
  author       = {Harvey, Brian and
                  Mönig, Jens and
                  Ball, Michael},
  title        = {Snap! Reference Manual},
  publisher    = {Zenodo},
  year         = 2025,
  month        = sep,
  doi          = {10.5281/zenodo.16892852},
  url          = {https://doi.org/10.5281/zenodo.16892852},
}

License¶

This work is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International