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CHALLENGE.MD

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Challenge : day 6 🐉

Prerequisites ✅

  • Make sure you've read all the instructions on how to complete the challenges.

  • Follow along with the daily guide.

Coding 🧑‍💻

The goal of today is to create our own NFT standard. 😎

  • Challenge 1 : Create an actor in main.mo and declare the following types.

    • TokenIndex of type Nat.
    • Error which is a variant type with multiples tags :

  • Challenge 2 : Declare an HashMap called registry with Key of type TokenIndex and value of type Principal. This will keeep track of which principal owns which TokenIndex.

  • Challenge 3 : Declare a variable of type Nat called nextTokenIndex, initialized at 0 that will keep track of the number of minted NFTs.
    Write a function called mint that takes no argument.
    This function should :

    • Returns a result of type Result and indicate an error in case the caller is anonymous.
    • If the user is authenticated : associate the current TokenIndex with the caller (use the HashMap we've created) and increase nextTokenIndex.

  • Challenge 4 : Write a function called transfer that takes two arguments :

    • to of type Principal.
    • tokenIndex of type Nat.

This function will transfer ownership of tokenIndex to the specified principal. You will check for eventuals errors and returns a result of type Result.

  • Challenge 5 : Write a function called balance that takes no arguments but returns a list of tokenIndex owned by the called.

  • Challenge 6 : Write a function called http_request that should return a message indicating the number of nft minted so far and the principal of the latest minter. (Use the section on http request in the daily guide).

  • Challenge 7 : Modify the actor so that you can safely upgrade it without loosing any state.

Well... you've just created your own NFT standard 🔥.

Bonus : intercanister calls.

  • Challenge 8 : Create another canister and use to mint a NFT by calling the mint method of your first canister.

Well... you just created your own on-chain wallet. 🔒

Bonus optional (Only take on those challenges if you have nothing else to do today...)

Ledger canister 💰

  • Challenge 9 : In a new actor implement a function called default_account that returns the address of the subbacount 0 for the canister.

  • Challenge 10 : Write two functions :

    • balance : takes no arguments and returns the balance of icps of the canister defaul account.
    • transfer : takes

Ressources for challenge 9 & 10.

  • Lectures on the ledger canister :
  • Example of icp in canister :

Good luck 🎉