In Dyalog APL, could G be recognized as an idiom that evaluates to F since F is more efficient?

How to change the solution from the answer to the question Dyalog APL: How to filter an array like filter()
To:

For Object class from Dyalog APL: How to write array of Objects to XML File?.

I have Object class like that:

I want to execute a function for each element of its left and right argument, by pair.

I am a beginner in APL (I use dyalog APL) and I want to change the value of a variable defined outside the function.