Creating a Fungible Token

Much the same as creating an NFT, Clarity also makes creating a fungible token (FT) trivial as well.

The process and code are much the same.

Trait

Just like with the NFT, it's a good idea to create a trait when you create a fungible token so that different tools and protocols and be confident in building interfaces for those tokens.

Since FTs may be divisible, the FT official mainnet deployment trait address has additional functions.

(define-trait sip-010-trait
  (
    ;; Transfer from the caller to a new principal
    (transfer (uint principal principal (optional (buff 34))) (response bool uint))

    ;; the human readable name of the token
    (get-name () (response (string-ascii 32) uint))

    ;; the ticker symbol, or empty if none
    (get-symbol () (response (string-ascii 32) uint))

    ;; the number of decimals used, e.g. 6 would mean 1_000_000 represents 1 token
    (get-decimals () (response uint uint))

    ;; the balance of the passed principal
    (get-balance (principal) (response uint uint))

    ;; the current total supply (which does not need to be a constant)
    (get-total-supply () (response uint uint))

    ;; an optional URI that represents metadata of this token
    (get-token-uri () (response (optional (string-utf8 256)) uint))
  )
)

Now let's see how we might implement this in Clarity, just like we would an NFT.

Clarity Code

(impl-trait 'SP3FBR2AGK5H9QBDH3EEN6DF8EK8JY7RX8QJ5SVTE.sip-010-trait-ft-standard.sip-010-trait)


(define-constant contract-owner tx-sender)
(define-constant err-owner-only (err u100))
(define-constant err-not-token-owner (err u101))

;; No maximum supply!
(define-fungible-token clarity-coin)

(define-public (transfer (amount uint) (sender principal) (recipient principal) (memo (optional (buff 34))))
    (begin
        (asserts! (is-eq tx-sender sender) err-not-token-owner)
        (try! (ft-transfer? clarity-coin amount sender recipient))
        (match memo to-print (print to-print) 0x)
        (ok true)
    )
)

(define-read-only (get-name)
    (ok "Clarity Coin")
)

(define-read-only (get-symbol)
    (ok "CC")
)

(define-read-only (get-decimals)
    (ok u6)
)

(define-read-only (get-balance (who principal))
    (ok (ft-get-balance clarity-coin who))
)

(define-read-only (get-total-supply)
    (ok (ft-get-supply clarity-coin))
)


(define-read-only (get-token-uri)
    (ok none)
)


(define-public (mint (amount uint) (recipient principal))
    (begin
        (asserts! (is-eq tx-sender contract-owner) err-owner-only)
        (ft-mint? clarity-coin amount recipient)
    )
)