have h : t = t2 := HasType_det ht1 ht2
case found
e : Exp
t : Ty
h ht1 : HasType e t
t2 : Ty
ht2 : HasType e t2
a✝ : Maybe.found t2 ht2 ≠ Maybe.unknown
⊢ Maybe.found t2 ht2 = Maybe.found t h
case found
e : Exp
t : Ty
h✝ ht1 : HasType e t
t2 : Ty
ht2 : HasType e t2
a✝ : Maybe.found t2 ht2 ≠ Maybe.unknown
h : t = t2
⊢ Maybe.found t2 ht2 = Maybe.found t h✝