Update expression parser to support indirect column name references?

The following code (within an observable notebook cell) runs just fine:

{
  let df = aq.from([{ a: 1 }, { a: 2 }]);
  return df.derive({ b: row => row['a'] + 1 }).view(10);
}

But if I try and make the column name a variable, it fails:

{
  let df = aq.from([{ a: 1 }, { a: 2 }]);
  let col = 'a';
  return df.derive({ b: row => row[col] + 1 }).view(10);
}

I suppose I’m just not understanding the scope in which the lambda gets evaluated, or something. What is the right way to use variable names within the lambdas that get passed to derive?

Notebook: https://observablehq.com/@pwills/arquero-confusions

[jheer]

Arquero v2.1.3 includes a fix so that you should now be able to use params and self-contained expressions to specify column name references. The importable Arquero observable notebook has also been updated.

[ericemc3]

or

  const attr = "tags", r = /[\[\]]/g ;

  return aq.from([{ tags: "[1,2,3]" }]).derive({
    tags_cleaned5: aq.escape(d => d[attr].replace(/[\[\]]/g, "")),
    tags_cleaned6: `d => op.replace(d.${attr}, ${r}, "")`
  })