DRAFT-What you always wanted to know but could not find about block-based environments

Block-based environments are visual programming environments, which are becoming more and more popular because of their ease of use. The ease of use comes thanks to their intuitive graphical representation and structural metaphors (jigsaw-like puzzles) to display valid combinations of language constructs to the users. Part of the current popularity of block-based environments is thanks to Scratch. As a result they are often associated with tools for children or young learners. However, it is unclear how these types of programming environments are developed and used in general. So we conducted a systematic literature review on block-based environments by studying 152 papers published between 2014 and 2020, and a non-systematic tool review of 32 block-based environments. In particular, we provide a helpful inventory of block-based editors for end-users on different topics and domains. Likewise, we focused on identifying the main components of block-based environments, how they are engineered, and how they are used. This survey should be equally helpful for language engineering researchers and language engineers alike

Concurrent Circular Reference Attribute Grammars

Reference Attribute Grammars (RAGs) is a declarative executable formalism used for constructing compilers and related tools. Existing implementations support concurrent evaluation only with global evaluation locks. This may lead to long latencies in interactive tools, where interactive and background threads query attributes concurrently.We present lock-free algorithms for concurrent attribute evaluation, enabling low latency in interactive tools. Our algorithms support important extensions to RAGs like circular (fixed-point) attributes and higher-order attributes.We have implemented our algorithms in Java, for the JastAdd metacompiler. We evaluate the implementation on a JastAdd-specified compiler for the Java language, demonstrating very low latencies for interactive attribute queries, on the order of milliseconds. Furthermore, initial experiments show a speedup of about a factor 2 when using four parallel compilation threads

Concurrent Circular Reference Attribute Grammars (Extended Version)

Reference Attribute Grammars (RAGs) is a declarative executable formalism used for constructing compilers and related tools. Existing implementations support concurrent evaluation only with global evaluation locks. This may lead to long latencies in interactive tools, where interactive and background threads query attributes concurrently.We present lock-free algorithms for concurrent attribute evaluation, enabling low latency in interactive tools. Our algorithms support important extensions to RAGs like circular (fixed-point) attributes and higher-order attributes.We have implemented our algorithms in Java, for the JastAdd metacompiler. We evaluate the implementation on a JastAdd-specified compiler for the Java language, demonstrating very low latencies for interactive attribute queries, on the order of milliseconds. Furthermore, initial experiments show a speedup of about a factor 2 when using four parallel compilation threads