inductive ThingA where
| mkA
deriving Ord
instance : LE ThingA where
  le a b := (compare a b).isLE

instance (t₁ t₂ : ThingA) : Decidable (t₁ <= t₂) := inferInstance
-- TODO: we may want to suppress the name of nested instances
#check instDecidableLeThingAInstLEThingA

inductive ThingB where
| mkB
deriving Ord
instance : LE ThingB where
  le a b := (compare a b).isLE
instance (t₁ t₂ : ThingB) : Decidable (t₁ <= t₂) := inferInstance
#check instDecidableLeThingBInstLEThingB