Sequences

Sequences

The pros and cons of sequences (as in the JavaFX interpreter now) vs immutable arrays were discussed:

	Everything is a sequence (as in the JavaFX interpreter now)	Arrays are different from singletons (immutable arrays)
Singleton	Singleton is a sequence of length one	Singleton can be automatically coerced to array
Type	Cardinality orthogonal to type	Cardinality part of type
Object	Is NOT an Object	IS an Object
null	Is an empty sequence	Is an Object value  ([] is empty array)
Down conversion to singleton	Automatic: last element	Explicit: first, last, only if singleton, etc
Nesting allowed	No nesting -- always flat	Nestable
Flattening	Flat by definition	Need concatenation and/or flattening operator
Pros		Familiarity (e.g., javascript, Java) Java interoperability Can nest
Cons	Automatic down conversion is counterintuitive Gilad: "The fact that arrays are not objects is terrible"	Need explicit operator to flatten Different than other Objects -- immutable (copy on assign) Object methods (e.g., hashcode) on array is array operation or Object operation?

No consensus. No strong opinions.

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Comments

It seems to me that the current situation is pretty good. You get the helpful flattening behavior by using arrays, and if you want to do nesting you just put objects in the arrays, and use a property. That seems like the best of both worlds, in this programming domain. Users mostly see things that are flattened, not nested, so a UI language needs to be pretty good at flattening in general. Rossjudson 21:44, 1 March 2008 (UTC)

What is the meaning of flattened?