An example of a simple Domain-Specific Language created with PEG.js.
The language is a sort-of TSV, where spaces separate cell values, and the header row is mandatory. The grammar allows C-like identifiers within the header, and integers only as values. A brutal check on the number of columns is also performed, to ensure the well-formedness of the code.
Valid code produces an array of objects representing the described data, that is then rendered as a table in a separate view.
Basic error messages are available in the editor’s status bar.