# Pastebin FAxmIRji
raku -MJSON::Fast -e '
loop {
  say to-json :!pretty, %(:type<bla>, :a(^100 .pick))
}
' | bin/eel -e='
  event ble {
    has $a1 = #1.a;
    has $a2 = #2.a;
    match {
      bla(#1, a == 42)
      bla(#2, a == 13)
    }
  }
'

{"a1":42,"type":"ble","timestamp":"2020-02-19T14:40:15.055072Z","a2":13}
{"a1":42,"type":"ble","timestamp":"2020-02-19T14:40:15.110054Z","a2":13}
{"a1":42,"type":"ble","timestamp":"2020-02-19T14:40:15.218650Z","a2":13}
{"a1":42,"a2":13,"type":"ble","timestamp":"2020-02-19T14:40:15.259750Z"}
{"a1":42,"a2":13,"type":"ble","timestamp":"2020-02-19T14:40:15.300648Z"}
{"timestamp":"2020-02-19T14:40:15.325864Z","type":"ble","a2":13,"a1":42}
{"timestamp":"2020-02-19T14:40:15.357166Z","type":"ble","a2":13,"a1":42}
{"a2":13,"type":"ble","timestamp":"2020-02-19T14:40:15.371284Z","a1":42}
{"timestamp":"2020-02-19T14:40:15.415902Z","type":"ble","a2":13,"a1":42}
^C