In almost all programming languages, expressions evaluating to no or many values must resort to special encodings, such as null values and containers, whose subsequent handling requires annoying coding idioms such as branching on not-null, iteration, or unwrapping. By introducing number as grammatical category that is orthogonal to type, and by letting expressions evaluate to a number of objects, rather than just one, the treatment of none, one, and many objects can be unified, leading to programs that are easier to write, read, and maintain (see https://drops.dagstuhl.de/opus/volltexte/2015/5032/pdf/22.pdf for the main ideas).

The corona pandemic exacerbates inequalities among scientists: while some can enjoy the silence of their home offices and use it to reach previously unknown levels of productivity, others suffer from the combination of working at home with home schooling, and from coping with the horror that the extradition of their children to the internet, as promoted by a naive public, means. In this situation, the staff of Schloss Dagstuhl has hosted me and allowed me to complete my above-sketched work in their familiar, friendly, and perfectly organized environment.

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Friedrich Steimann