Although APL is the original array programming language, it has never had a general notation for entering multi-dimensional arrays. This talk tells the decade-long story of designing, specifying, and implementing APL’s answer to JavaScript’s JSON. Despite several ISO standards, the various APL implementations have diverged from each other over time, so a new array notation needed to be defined in a way that was compatible with these different “flavours”, as well as being convenient to type and easy for non-APL tools to process. The resulting APL Array Notation specification document has not yet been adopted as an official standard, but it has been designed and written in such a way that would facilitate this process.

Lifelong APL programmer, founder of the APL Orchard, and the creator of APLcart. Head of Language Design at Dyalog Ltd.