First Class Values

In OpenSCAD2, every thing that can be referenced or manipulated by OpenSCAD code is a first class value. This means:

It can be passed as an argument to a function.
It can be returned as a result from a function.
It can be an element of a list.
It can be written as a literal expression. This means we have anonymous function literals.
It can be printed as a valid OpenSCAD expression using echo.
It can be given a name using definition syntax: name = value;.

This can't happen until the variable, function and module namespaces have been unified into a single namespace. Fixed by Definitions and Scoping.

The goal of First Class Values is to improve composability.

Violations of First Class Values in OpenSCAD1

Functions and modules are not first class. Fixed by Functions.
Shapes are not first class.
Groups are not first class. Fixed by Objects.
Number are not first class, because 1/0 prints as inf, and 0/0 prints as nan, but neither inf nor nan are valid expressions. Fixed by Simple Values.