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ivan.gavlik
ivan.gavlik

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(Clojure Managing-User-Permissions)

#functional #tutorial #beginners #clojure

Clojure practice task:

Managing User Permissions with Sets

You are developing a role-based access control system for a web application. Each user has a set of permissions (e.g., :read, :write, :delete). Your goal is to implement a permission management system using Clojure sets.

User {:user-name :email :permission}

The set of all available permissions in the system is :read :write :delete.

Tasks

Create a function to assign a set of permissions to a user.

(defn valid-user-permission? [permission]
  (subset? permission #{:read :write :delete}))

(defn valid-user? [user]
  (and (some? (:user-name user))
       (some? (:email user))))

(defn assign-user-permissions [user permissions]
  (when (and (valid-user? user) (valid-user-permission? permissions))
    (assoc user :permissions permissions)))
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Write a function to check if a user has a specific permission.

(defn has-user-permission? [user permission]
  (when (and (valid-user? user) (valid-user-permission? #{permission}))
    (contains? (:permissions user) permission)))
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Write a function to revoke a specific permission from a user.

(defn revoke-user-permissions [user permission]
  (when (and (valid-user? user) (valid-user-permission? #{permission}))
    (let [current-p (:permissions user)
          remove-p (disj current-p permission)]
      (assoc user :permissions remove-p)
      )))
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Find users who have at least one common permission from a given permission set.

(defn find-users-common-permissions [users permissions]
  (filter #(subset? permissions (:permissions %)) users))
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Find users who have all required permissions from a given permission set.

(defn find-users-all-permissions [users permissions]
  (filter #(= permissions (:permissions %)) users))
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Compute the difference between two users permissions.

(defn diff-users-permissions [user-1 user-2]
  (difference (:permissions user-1) (:permissions user-2)))
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Generate a report of all users and their permissions.
Example Alice -> #{:read :write}

(defn users-permissions-report [users]
  (map #(let [user (:user-name %)
              permissions (:permissions %) ]
          (cond
            (some? permissions) (str user " -> " permissions)
            :else (str user)
            ))
       users))
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Top comments (1)

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André Borba •

Hi Ivan, how are you? I hope you're doing well! :)

I really liked your implementation and wanted to share a suggestion. What do you think about using clojure.spec for validations instead of creating separate validator functions? I feel it could be a more natural way to handle this in Clojure. It would let you cleanly separate attribute validations from business logic in a scalable way, plus you’d get better error handling and richer feedback beyond just "true or false." What do you think?