I recall another language that was trying to do something similar. In most languages you have to decide about x:1 versus x:* relationships very early and it’s a painful refactor to go back and fix it. This one tried to fix it as well so that much of the time you only changed the variable declaration and the code just worked.

jQuery made a similar observation, and many of its functions are list comprehensions. If they had chosen a different default behavior for empty lists I might still be championing it today. But the silent failures were a bitter pill to swallow.

In fact I sometimes still fantasize about building a mini front end framework containing the inverse behavior and some other more modern ideas.