can i combine 2 lensen to something that sets and gets 2 values?

# arrow

[christophsturm]

can i combine 2 lensen to something that sets and gets 2 values?

[simon.vergauwen]

Sadly not without it implying to copy twice.

[simon.vergauwen]

Only if you write a custom instance

[simon.vergauwen]

You can also use this: https://stackoverflow.com/questions/58104502/changing-multiple-attributes-of-a-data-class-with-a-lens/58134647#58134647

[christophsturm]

ok but that looks like it will copy twice

[simon.vergauwen]

Yes, it will indeed copy twice. The only other way is to write a custom Optic, or to use modify + copy.
For example:

Employee.company.address.street.name
  .aside(Employee.company.address.street.number)
  .modify(json) { Pair("", 5) }

Employee.company.address.street.modify(json) {
  it.copy(name = "", number = 5)
}

[simon.vergauwen]

Using Optics + copy can still give you the benefit without having to write a custom Optic.
Not that it only works if you are "focusing" on a data class.

[christophsturm]

modify + copy is really useful, thanks!