record-trait-quantified-field-transform.cx

import dict

trait PD {
  pd: self => ()
}

impl PD String {
  pd = print
}

impl PD Number {
  pd = print
}

fun constrainType<T: Ordered+PD>(x: T): T {
  x
}

impl PD {...} {
  for fieldValue { constrainType(fieldValue) }
  pd(r) {
    let d = dict.from(fieldMap(r))
    for item in sorted(d->items()) {
      let (key, value) = item
      print(key)
      pd(value)
    }
  }
}

fun main() {
  pd({x: "hello", y: "world"})
  pd({a: 10, b: 20})
}