Mapping letters to modifiers

[kenNash]

I'm trying to make a to behave as a normal a when pressed alone, and as the modifier ⇧ in combos like ⌘⇧K.
The same for

• s and ⌃
• d and ⌥
• f and ⌘

The following code is effective to manage a alone, and a as “shift”, but not in combos like ⌘⇧K.

rule("A")
  .manipulators([
      map('a')
        .toIfAlone("a", {}, { halt: true })
        .toIfHeldDown("‹⇧"),
 ])

I'm trying to implement a

withModifier('??')({
  // a: toKey('‹⇧'), // Shift
  s: toKey('‹⌃'), // Control
  d: toKey('‹⌥'), // Option
  f: toKey('‹⌘'), // Command

functionality, without success.

Ideas?

[kenNash]

I'm experimenting with this:

rule("A")
      .manipulators([
        withModifier('optionalAny')([
          map('a')
            .toIfAlone("a", {}, { halt: true })
            .toIfHeldDown("‹⇧"),
          ]),
        ])

The same for the other 3 keys (and, specularly, with jkl;).

So far, it seems to work.