Theo B. Weidmann

About

I am a doctoral student in the Advanced Software Technologies (AST) Lab at ETH Zürich, supervised by Prof. Zhendong Su. I earned my Master’s in Computer Science with distinction from ETH Zürich. I have extensive industry experience, including work as a JVM compiler engineer at Oracle and as a software engineer and interface designer at several start-ups.

My research interests lie in programming languages, software engineering, and computer science education. I study ways to make programming more accessible through visual and semantics-first programming approaches and AI-assisted programming.

I am the creator of Emojicode (3,000+ stars on GitHub), a programming language consisting of emojis, which appeared in the Fall 2021 test of CS50 at Harvard and Yale and has its own course at Codecademy. At ETH, I co-designed Algot, a visual language pioneering semantics-first programming, allowing us to prototype, explore and compare different paradigms for early programming education.

Publications

• Computer Science Achievement and Writing Skills Predict Vibe Coding Proficiency
  Sverrir Thorgeirsson*, Theo B. Weidmann*, Zhendong Su* Equal contribution
  In Proceedings of CHI, Barcelona, Spain, April 13-17, 2026.
  arxiv
• The Elephant in the Syntax: A Comparative Study of Semantics-First, Block-Based, and Textual Programming
  Theo B. Weidmann*, Sverrir Thorgeirsson*, Karl-Heinz Weidmann, April Yi Wang, Zhendong Su* Equal contribution
  In Proceedings of CHI, Barcelona, Spain, April 13-17, 2026.
  pdf
• Map, Filter, and Conquer: A Visual Tool for Learning Higher-Order Functions
  Silvan Renggli, Sverrir Thorgeirsson, Theo B. Weidmann, Zhendong Su
  In Proceedings of ITiCSE, Nijmegen, Netherlands, June 30-July 2, 2025.
  doi
• An Electroencephalography Study on Cognitive Load in Visual and Textual Programming
  Sverrir Thorgeirsson, Chengyu Zhang, Theo B. Weidmann, Karl-Heinz Weidmann, Zhendong Su
  In Proceedings of ICER, Melbourne, Australia, August 13-15, 2024.
  doi
• Recursion in Secondary Computer Science Education: A Comparative Study of Visual Programming Approaches
  Sverrir Thorgeirsson, Lennart Lais, Theo B. Weidmann, Zhendong Su
  In Proceedings of SIGCSE, Portland, OR, USA, March 20-23, 2024.
  doi
• Comparing Cognitive Load Among Undergraduate Students Programming in Python and the Visual Language Algot
  Sverrir Thorgeirsson*, Theo B. Weidmann*, Karl-Heinz Weidmann, Zhendong Su* Equal contribution
  In Proceedings of SIGCSE, Portland, OR, USA, March 20-23, 2024.
  doi
• Bridging the Syntax-Semantics Gap of Programming
  Theo B. Weidmann*, Sverrir Thorgeirsson*, Zhendong Su* Equal contribution
  In Proceedings of SPLASH/Onward!, Auckland, New Zealand, December 5-10, 2022.
  doi

Teaching and Mentored Students

I have been a teaching assistant for the following courses at ETH Zürich:

• Compiler Design (2025)
• Automated Software Testing (2025, 2026)

I have mentored the following students in their Bachelor’s and Master’s theses at ETH Zürich:

• Olivier Mattmann. "C2Fuzz: Effectively Fuzzing the HotSpot C2 JIT Compiler". Master's Thesis, 2026. Co-supervised by Manuel Hässig (Oracle) and Zhendong Su
• Patrice Delley. "From Play to Pattern: A Visual Game Approach to Teaching Computational Thinking". Master's Thesis, 2025. Co-supervised by Sverrir Thorgeirsson and Zhendong Su