arXiv subjects

Benedikt Fein

Publications and source records attributed to Benedikt Fein.

5 recordsLinked to original sources

arXiv2026

EmbeddedKittens: An Evaluation of Code Embeddings for Scratch

The trend of embedding source code for machine learning applications also enables new opportunities in learning analytics in programming education, but which code embedding approach is most suitable for learning analytics remains an open question. A common approach to embedding source code lies in treating the code as a token sequence similar to natural language when training large language models~(LLMs). However, in case of visual block-based programming languages like Scratch, this approach cannot be applied directly. While text-based representations of block-based code can be created to apply LLMs to this problem, other dedicated embedding models could potentially exhibit improved performance by capturing additional structural information. In this paper, we therefore instantiate four LLMs and five different popular embedding approaches for Scratch programs, create a token-prediction and two different classification tasks with corresponding datasets, and empirically evaluate the models on them. Our experiments demonstrate that a transfer of code embeddings to the educational environment of Scratch is feasible. The embedding models trained on large open Scratch datasets capture relevant structural and semantic information about the code to enable learning analytics like predicting functional correctness of student programs, in the typically small classroom setting without requiring further task-specific model fine-tuning.

cs.SE↗

arXiv2025

Detecting Gender Stereotypes in Scratch Programming Tutorials

Gender stereotypes in introductory programming courses often go unnoticed, yet they can negatively influence young learners' interest and learning, particularly under-represented groups such as girls. Popular tutorials on block-based programming with Scratch may unintentionally reinforce biases through character choices, narrative framing, or activity types. Educators currently lack support in identifying and addressing such bias. With large language models~(LLMs) increasingly used to generate teaching materials, this problem is potentially exacerbated by LLMs trained on biased datasets. However, LLMs also offer an opportunity to address this issue. In this paper, we explore the use of LLMs for automatically identifying gender-stereotypical elements in Scratch tutorials, thus offering feedback on how to improve teaching content. We develop a framework for assessing gender bias considering characters, content, instructions, and programming concepts. Analogous to how code analysis tools provide feedback on code in terms of code smells, we operationalise this framework using an automated tool chain that identifies *gender stereotype smells*. Evaluation on 73 popular Scratch tutorials from leading educational platforms demonstrates that stereotype smells are common in practice. LLMs are not effective at detecting them, but our gender bias evaluation framework can guide LLMs in generating tutorials with fewer stereotype smells.

cs.CY↗

arXiv2025

LitterBox+: An Extensible Framework for LLM-enhanced Scratch Static Code Analysis

Large language models (LLMs) have become an essential tool to support developers using traditional text-based programming languages, but the graphical notation of the block-based Scratch programming environment inhibits the use of LLMs. To overcome this limitation, we propose the LitterBox+ framework that extends the Scratch static code analysis tool LitterBox with the generative abilities of LLMs. By converting block-based code to a textual representation suitable for LLMs, LitterBox+ allows users to query LLMs about their programs, about quality issues reported by LitterBox, and it allows generating code fixes. Besides offering a programmatic API for these functionalities, LitterBox+ also extends the Scratch user interface to make these functionalities available directly in the environment familiar to learners. The framework is designed to be easily extensible with other prompts, LLM providers, and new features combining the program analysis capabilities of LitterBox with the generative features of LLMs. We provide a screencast demonstrating the tool at https://youtu.be/RZ6E0xgrIgQ.

cs.SE↗

arXiv2025

AsserT5: Test Assertion Generation Using a Fine-Tuned Code Language Model

Writing good software tests can be challenging, therefore approaches that support developers are desirable. While generating complete tests automatically is such an approach commonly proposed in research, developers may already have specific test scenarios in mind and thus just require help in selecting the most suitable test assertions for these scenarios. This can be done using deep learning models to predict assertions for given test code. Prior research on assertion generation trained these models specifically for the task, raising the question how much the use of larger models pre-trained on code that have emerged since then can improve their performance. In particular, while abstracting identifiers has been shown to improve specifically trained models, it remains unclear whether this also generalises to models pre-trained on non-abstracted code. Finally, even though prior work demonstrated high accuracy it remains unclear how this translates into the effectiveness of the assertions at their intended application -- finding faults. To shed light on these open questions, in this paper we propose AsserT5, a new model based on the pre-trained CodeT5 model, and use this to empirically study assertion generation. We find that the abstraction and the inclusion of the focal method are useful also for a fine-tuned pre-trained model, resulting in test assertions that match the ground truth assertions precisely in up to 59.5\% of cases, more than twice as precise as prior models. However, evaluation on real bugs from the Defects4J dataset shows that out of 138 bugs detectable with assertions in real-world projects, AsserT5 was only able to suggest fault-finding assertions for 33, indicating the need for further improvements.

cs.SE↗

arXiv2023

On the Applicability of Language Models to Block-Based Programs

Block-based programming languages like Scratch are increasingly popular for programming education and end-user programming. Recent program analyses build on the insight that source code can be modelled using techniques from natural language processing. Many of the regularities of source code that support this approach are due to the syntactic overhead imposed by textual programming languages. This syntactic overhead, however, is precisely what block-based languages remove in order to simplify programming. Consequently, it is unclear how well this modelling approach performs on block-based programming languages. In this paper, we investigate the applicability of language models for the popular block-based programming language Scratch. We model Scratch programs using n-gram models, the most essential type of language model, and transformers, a popular deep learning model. Evaluation on the example tasks of code completion and bug finding confirm that blocks inhibit predictability, but the use of language models is nevertheless feasible. Our findings serve as foundation for improving tooling and analyses for block-based languages.

cs.PL↗