instance_cache1.lean:5:2: error: failed to synthesize type class instance for A : Type, a : A, this : has_add A ⊢ has_add A instance_cache1.lean:8:7: error: failed to synthesize type class instance for A : Type, a : A, s : has_add A ⊢ has_add A instance_cache1.lean:11:19: error: failed to synthesize type class instance for A : Type, a : A, s : has_add A ⊢ has_add A