How to make more idiomatic

gistfile1.txt

primitive Inh
primitive Sim
primitive Imp
primitive Equ
primitive And
primitive Or
primitive Not

type Op is (Inh|Sim|Imp|Equ|And|Or|Not)
type Word is String

/* Ideally would like the following but recursive tyoes not allowed
type Relation is (Op, Array[Term])
*/

type Term is (Word|Relation)

class val Relation
  let term: (Op, Array[Term])

  new create(rel: Op, term': Array[Term]) =>
    term = (rel, term')

// Term needs to be sendable and immmutable

actor Main
  let t1: Term = "cat"
  let t2: Term = "animal"
  let t3: Term = recover val Relation(Inh, [t1, t2]) end
  let t4: Term = recover val Relation(Inh, [t1, t2]) end
  let t5: Term = recover val Relation(Equ, [t3, t3]) end

/* Is there a more idiomatic way of achiveing this, without using recovery
   I want to be able to decalre nested relations like the following:

  let t6: Term = Relation(Equ, [Relation(Imp, ["dog", "pet"]), Relation(Inh, ["cat", "pet"])])
*/

  new create(env: Env) =>
    env.out.print("Done")

If relations are normally going to be vals then you can change line 21 to be

new val create(rel: Op, term': Array[Term])

This will make something like

Relation(Inh, [t1, t2])

default to being a val