Avoid using the pipe operator just once.

lib/real_world/accounts/users.ex

@@ -23,9 +23,7 @@ defmodule RealWorld.Accounts.Users do
   end
 
   def unfollow(user, followee) do
-    relation =
-      UserFollower
-      |> Repo.get_by(user_id: user.id, followee_id: followee.id)
+    relation = Repo.get_by(UserFollower, user_id: user.id, followee_id: followee.id)
 
     case relation do
       nil ->

lib/real_world_web/controllers/article_controller.ex

@@ -19,7 +19,8 @@ defmodule RealWorldWeb.ArticleController do
 
   def index(conn, params, user) do
     articles =
-      Blog.list_articles(params)
+      params
+      |> Blog.list_articles()
       |> Repo.preload([:author, :favorites])
       |> Blog.load_favorites(user)
 
@@ -37,9 +38,7 @@ defmodule RealWorldWeb.ArticleController do
 
   def create(conn, %{"article" => params}, user) do
     with {:ok, %Article{} = article} <- Blog.create_article(create_params(params, user)) do
-      article =
-        article
-        |> Repo.preload([:author, :favorites])
+      article = Repo.preload(article, [:author, :favorites])
 
       conn
       |> put_status(:created)
@@ -49,8 +48,7 @@ defmodule RealWorldWeb.ArticleController do
   end
 
   defp create_params(params, user) do
-    params
-    |> Map.merge(%{"user_id" => user.id})
+    Map.merge(params, %{"user_id" => user.id})
   end
 
   def show(conn, %{"id" => slug}, user) do
@@ -76,9 +74,7 @@ defmodule RealWorldWeb.ArticleController do
   end
 
   def favorite(conn, %{"slug" => slug}, user) do
-    article =
-      slug
-      |> Blog.get_article_by_slug!()
+    article = Blog.get_article_by_slug!(slug)
 
     with {:ok, %Favorite{}} <- Blog.favorite(user, article) do
       article =
@@ -91,9 +87,7 @@ defmodule RealWorldWeb.ArticleController do
   end
 
   def unfavorite(conn, %{"slug" => slug}, user) do
-    article =
-      slug
-      |> Blog.get_article_by_slug!()
+    article = Blog.get_article_by_slug!(slug)
 
     with {:ok, _} <- Blog.unfavorite(article, user) do
       article =

lib/real_world_web/controllers/comment_controller.ex

@@ -10,11 +10,10 @@ defmodule RealWorldWeb.CommentController do
   plug(Guardian.Plug.EnsureAuthenticated when action in [:create, :update, :delete])
 
   def index(conn, %{"article_id" => slug}, _user) do
-    article = Blog.get_article_by_slug!(slug)
-    comments = Blog.list_comments(article)
-
     comments =
-      comments
+      slug
+      |> Blog.get_article_by_slug!()
+      |> Blog.list_comments()
       |> RealWorld.Repo.preload(:author)
 
     render(conn, "index.json", comments: comments)

lib/real_world_web/controllers/profile_controller.ex

@@ -25,8 +25,7 @@ defmodule RealWorldWeb.ProfileController do
   def follow(conn, %{"username" => username}, current_user) do
     case Users.get_by_username(username) do
       followee = %User{} ->
-        current_user
-        |> Users.follow(followee)
+        Users.follow(current_user, followee)
 
         conn
         |> put_status(:ok)
@@ -46,8 +45,7 @@ defmodule RealWorldWeb.ProfileController do
   def unfollow(conn, %{"username" => username}, current_user) do
     case Users.get_by_username(username) do
       followee = %User{} ->
-        current_user
-        |> Users.unfollow(followee)
+        Users.unfollow(current_user, followee)
 
         conn
         |> put_status(:ok)

lib/real_world_web/controllers/session_controller.ex

@@ -8,8 +8,7 @@ defmodule RealWorldWeb.SessionController do
   def create(conn, params) do
     case Auth.find_user_and_check_password(params) do
       {:ok, user} ->
-        {:ok, jwt, _full_claims} =
-          user |> RealWorldWeb.Guardian.encode_and_sign(%{}, token_type: :token)
+        {:ok, jwt, _full_claims} = RealWorldWeb.Guardian.encode_and_sign(user, %{}, token_type: :token)
 
         conn
         |> put_status(:created)

lib/real_world_web/controllers/user_controller.ex

@@ -11,8 +11,7 @@ defmodule RealWorldWeb.UserController do
   def create(conn, %{"user" => user_params}, _) do
     case Auth.register(user_params) do
       {:ok, user} ->
-        {:ok, jwt, _full_claims} =
-          user |> RealWorldWeb.Guardian.encode_and_sign(%{}, token_type: :token)
+        {:ok, jwt, _full_claims} = RealWorldWeb.Guardian.encode_and_sign(user, %{}, token_type: :token)
 
         conn
         |> put_status(:created)