Getting grammars into shape for block-based editors

Block-based environments are visual programming environments that allow users to program by interactively arranging visual jigsaw-like blocks. They have shown to be helpful in several domains but often require experienced developers for their creation. Previous research investigated the use of language workbenches to generate block-based editors based on grammars, but the generated block-based editors sometimes provided too many unnecessary blocks, leading to verbose environments and programs. To reduce the number of interactions, we propose a set of transformations to simplify the original grammar, yielding a reduction of the number of (useful) kinds of blocks available in the resulting editors. We show that our generated block-based editors are improved for a set of observed aesthetic criteria up to a certain complexity. As such, analyzing and simplifying grammars before generating block-based editors allows us to derive more compact and potentially more usable block-based editors, making reuse of existing grammars through automatic generation feasible.