> But that would mean optimising for "hello world" and other small script scenarios, which isn't a goal of the language design.

Fairly complex programs can be written with just plain functions, all of them elegantly starting off column 0 instead of being tabbed for namespaces and classes. It works especially well with directory structure based namespaces. eg: Microsoft's own TypeScript.

> Like "dynamic" in C# 4 ?

No not dynamic, I wouldn't use that very much either. https://en.wikipedia.org/wiki/Structural_type_system