[data-shapes] Node Expressions : definition and evaluation (#322)

afs has just created a new issue for https://github.com/w3c/data-shapes:

== Node Expressions : definition and evaluation ==
The current (2025-03-12) definition of Node Expression read as:

> Each node expression function has an IRI as its function name.
> Node expression functions can declare one or more node expression parameters.
> Each of these parameters has an IRI.

as if the only way to invoke a function is by its function name which isn't true (IRI expression, literal expression).

Alternative:

A node expression is one of

* A function called by its function name
* An IRI expression
* A literal expression


and the definitions of "IRI expression" and "literal expression" need changing (they can be used as direct terms or via their function name).

Evaluation is defined as `eval(expr, activeGraph, scope)` 

How to paramaters and positional arguments e.g. `[ fn:strlen ( someWayToGetInputFocuNode 2 3 ) ]`
get passed to the evaluation step?

1. What goes in `scope`?
2. Does default properties modify the active graph during evaluation?
3. Positional arguments are not in the node expression definition.


Please view or discuss this issue at https://github.com/w3c/data-shapes/issues/322 using your GitHub account


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