[goto11]

So it is a language with single-character symbols for the most common array operations like map, filter etc.

I think the article tries to make it sound more mysterious and groundbreaking than it really is.

[mr_vile]

the symbols compose in both directions and are aware of tacit parameters, so I don't really think your summary is even remotely correct

[goto11]

By "compose in both directions" you mean like arithmetic operators like + and * ? No doubt it is useful to have built-in operators for array operations if you have to do a lot of array operations.