{motive : Lean.IR.SimpleGroundExpr → Sort u} →
  (t : Lean.IR.SimpleGroundExpr) →
    t.ctorIdx = 2 →
      ((func : Lean.IR.FunId) →
          (args : Array Lean.IR.SimpleGroundArg) → motive (Lean.IR.SimpleGroundExpr.pap func args)) →
        motive t