style(library): rename set_category to discrete_category

library/algebra/category/constructions.lean

@@ -70,20 +70,20 @@ namespace category
       (λh f, empty.rec _ f) f)
     (λh (g : empty), empty.rec _ g) g
   omit H
-  definition set_category (A : Type) [H : decidable_eq A] : category A :=
+  definition discrete_category (A : Type) [H : decidable_eq A] : category A :=
   mk (λa b, set_hom a b)
      (λ a b c g f, set_compose g f)
      (λ a, decidable.rec_on_true rfl ⋆)
      (λ a b c d h g f, @subsingleton.elim (set_hom a d) _ _ _)
      (λ a b f, @subsingleton.elim (set_hom a b) _ _ _)
      (λ a b f, @subsingleton.elim (set_hom a b) _ _ _)
-  definition Set_category (A : Type) [H : decidable_eq A] := Mk (set_category A)
+  definition Discrete_category (A : Type) [H : decidable_eq A] := Mk (discrete_category A)
   end
   section
   open unit bool
-  definition category_one := set_category unit
+  definition category_one := discrete_category unit
   definition Category_one := Mk category_one
-  definition category_two := set_category bool
+  definition category_two := discrete_category bool
   definition Category_two := Mk category_two
   end
 

library/algebra/category/default.lean

@@ -2,4 +2,4 @@
 -- Released under Apache 2.0 license as described in the file LICENSE.
 -- Author: Floris van Doorn
 
-import .basic .morphism .functor .constructions
+import .morphism .constructions

library/logic/eq.lean

@@ -90,7 +90,7 @@ namespace eq
   drec_on H rfl
 
   theorem rec_on_constant2 (H₁ : a₁ = a₂) (H₂ : a₃ = a₄) (b : B) : rec_on H₁ b = rec_on H₂ b :=
-  rec_on_constant H₁ b ⬝ (rec_on_constant H₂ b)⁻¹
+  rec_on_constant H₁ b ⬝ rec_on_constant H₂ b⁻¹
 
   theorem rec_on_irrel_arg {f : A → B} {D : B → Type} (H : a = a') (H' : f a = f a') (b : D (f a)) :
                        rec_on H b = rec_on H' b :=