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Can Advanced Type Systems Be Usable? An Empirical Study of Ownership, Assets, and Typestate in Obsidian (Artifact)

Coblenz, Michael; Aldrich, Jonathan; Myers, Brad A.; Sunshine, Joshua


Some blockchain programs (smart contracts) have included serious security vulnerabilities. Obsidian is a new typestate-oriented programming language that uses a strong type system to rule out some of these vulnerabilities. Although Obsidian was designed to promote usability to make it as easy as possible to write programs, strong type systems can cause a language to be difficult to use. In particular, ownership, typestate, and assets, which Obsidian uses to provide safety guarantees, have not seen broad adoption together in popular languages and result in significant usability challenges. We performed an empirical study with 20 participants comparing Obsidian to Solidity, which is the language most commonly used for writing smart contracts today. We observed that Obsidian participants were able to successfully complete more of the programming tasks than the Solidity participants. We also found that asset-related bugs, which Obsidian detects at compile time, were commonly accidentally inserted by the Solidity participants.


The artifact supports replication of the experiment described in the paper. For instructions regarding how to use the artifact, please see the included artifact evaluation guide.

Additional funding sources: NSA award H9823018D0008 NSF award CCF1901033 USAF award FA8702-15-D-0002 IBM Ripple
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