Functions
The complete reference guide to all Clarity functions.
- (subtract)
Introduced in: Clarity 1
input: int, ... | uint, ...
output: int | uint
signature: (- i1 i2...)
description: Subtracts a variable number of integer inputs and returns the result. In the event of an underflow, throws a runtime error.
example:
(- 2 1 1) ;; Returns 0
(- 0 3) ;; Returns -3* (multiply)
Introduced in: Clarity 1
input: int, ... | uint, ...
output: int | uint
signature: (* i1 i2...)
description: Multiplies a variable number of integer inputs and returns the result. In the event of an overflow, throws a runtime error.
example:
(* 2 3) ;; Returns 6
(* 5 2) ;; Returns 10
(* 2 2 2) ;; Returns 8/ (divide)
Introduced in: Clarity 1
input: int, ... | uint, ...
output: int | uint
signature: (/ i1 i2...)
description: Integer divides a variable number of integer inputs and returns the result. In the event of division by zero, throws a runtime error.
example:
+ (add)
Introduced in: Clarity 1
input: int, ... | uint, ...
output: int | uint
signature: (+ i1 i2...)
description: Adds a variable number of integer inputs and returns the result. In the event of an overflow, throws a runtime error.
example:
< (less than)
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: bool
signature: (< i1 i2)
description:
Compares two integers, returning true if i1 is less than i2 and false otherwise. i1 and i2 must be of the same type. Starting with Stacks 1.0, the <-comparable types are int and uint. Starting with Stacks 2.1, the <-comparable types are expanded to include string-ascii, string-utf8 and buff.
example:
<= (less than or equal)
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: bool
signature: (<= i1 i2)
description:
Compares two integers, returning true if i1 is less than or equal to i2 and false otherwise. i1 and i2 must be of the same type. Starting with Stacks 1.0, the <=-comparable types are int and uint. Starting with Stacks 2.1, the <=-comparable types are expanded to include string-ascii, string-utf8 and buff.
example:
> (greater than)
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: bool
signature: (> i1 i2)
description:
Compares two integers, returning true if i1 is greater than i2 and false otherwise. i1 and i2 must be of the same type. Starting with Stacks 1.0, the >-comparable types are int and uint. Starting with Stacks 2.1, the >-comparable types are expanded to include string-ascii, string-utf8 and buff.
example:
>= (greater than or equal)
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: bool
signature: (>= i1 i2)
description:
Compares two integers, returning true if i1 is greater than or equal to i2 and false otherwise. i1 and i2 must be of the same type. Starting with Stacks 1.0, the >=-comparable types are int and uint. Starting with Stacks 2.1, the >=-comparable types are expanded to include string-ascii, string-utf8 and buff.
example:
and
Introduced in: Clarity 1
input: bool, ...
output: bool
signature: (and b1 b2 ...)
description:
Returns true if all boolean inputs are true. Importantly, the supplied arguments are evaluated in-order and lazily. Lazy evaluation means that if one of the arguments returns false, the function short-circuits, and no subsequent arguments are evaluated.
example:
append
Introduced in: Clarity 1
input: list A, A
output: list
signature: (append (list 1 2 3 4) 5)
description:
The append function takes a list and another value with the same entry type, and outputs a list of the same type with max_len += 1.
example:
as-contract
Deprecated in Clarity 4.
Introduced in: Clarity 1
input: A
output: A
signature: (as-contract expr)
description:
The as-contract function switches the current context's tx-sender value to the contract's principal and executes expr with that context. It returns the resulting value of expr.
example:
as-contract?
The previous version of as-contract, introduced in Clarity 1, has changed to as-contract? in Clarity 4, with several new security enhancements.
Introduced in: Clarity 4
input: ((Allowance){0,128}), AnyType, ... A
output: (response A uint)
signature: (as-contract? ((with-stx|with-ft|with-nft|with-stacking)*) expr-body1 expr-body2 ... expr-body-last)
description:
Switches the current context's tx-sender and contract-caller values to the contract's principal and executes the body expressions within that context, then checks the asset outflows from the contract against the granted allowances, in declaration order. If any allowance is violated, the body expressions are reverted, an error is returned, and an event is emitted with the full details of the violation to help with debugging. Note that the allowance setup expressions are evaluated before executing the body expressions. The final body expression cannot return a response value in order to avoid returning a nested response value from as-contract? (nested responses are error-prone). Returns:
(ok x)if the outflows are within the allowances, wherexis the result of the final body expression and has typeA.(err index)if an allowance was violated, whereindexis the 0-based index of the first violated allowance in the list of granted allowances, oru128if an asset with no allowance caused the violation.
example:
as-max-len?
Introduced in: Clarity 1
input: sequence_A, uint
output: (optional sequence_A)
signature: (as-max-len? sequence max_length)
description:
The as-max-len? function takes a sequence argument and a uint-valued, literal length argument. The function returns an optional type. If the input sequence length is less than or equal to the supplied max_length, this returns (some sequence), otherwise it returns none. Applicable sequence types are (list A), buff, string-ascii and string-utf8.
example:
asserts!
Introduced in: Clarity 1
input: bool, C
output: bool
signature: (asserts! bool-expr thrown-value)
description:
The asserts! function admits a boolean argument and asserts its evaluation: if bool-expr is true, asserts! returns true and proceeds in the program execution. If the supplied argument is returning a false value, asserts! returns thrown-value and exits the current control-flow.
example:
at-block
Deprecated in Clarity 5.
As of Epoch 3.4, existing contracts using at-block will throw an error if called.
Introduced in: Clarity 1
input: (buff 32), A
output: A
signature: (at-block id-block-hash expr)
description: Removed in Epoch 3.4 (see SIP-042).
The at-block function evaluates the expression expr as if it were evaluated at the end of the block indicated by the block-hash argument. The expr closure must be read-only.
Note: The block identifying hash must be a hash returned by the id-header-hash block information property. This hash uniquely identifies Stacks blocks and is unique across Stacks forks. While the hash returned by header-hash is unique within the context of a single fork, it is not unique across Stacks forks.
The function returns the result of evaluating expr.
example:
begin
Introduced in: Clarity 1
input: AnyType, ... A
output: A
signature: (begin expr1 expr2 expr3 ... expr-last)
description:
The begin function evaluates each of its input expressions, returning the return value of the last such expression.
Note: intermediary statements returning a response type must be checked.
example:
bit-and
Introduced in: Clarity 2
input: int, ... | uint, ...
output: int | uint
signature: (bit-and i1 i2...)
description: Returns the result of bitwise and'ing a variable number of integer inputs.
example:
bit-not
Introduced in: Clarity 2
input: int | uint
output: int | uint
signature: (bit-not i1)
description:
Returns the one's compliement (sometimes also called the bitwise compliment or not operator) of i1, effectively reversing the bits in i1. In other words, every bit that is 1 in ì1 will be 0 in the result. Conversely, every bit that is 0 in i1 will be 1 in the result.
example:
bit-or
Introduced in: Clarity 2
input: int, ... | uint, ...
output: int | uint
signature: (bit-or i1 i2...)
description: Returns the result of bitwise inclusive or'ing a variable number of integer inputs.
example:
bit-shift-left
Introduced in: Clarity 2
input: int, uint | uint, uint
output: int | uint
signature: (bit-shift-left i1 shamt)
description:
Shifts all the bits in i1 to the left by the number of places specified in shamt modulo 128 (the bit width of Clarity integers).
Note that there is a deliberate choice made to ignore arithmetic overflow for this operation. In use cases where overflow should be detected, developers should use *, /, and pow instead of the shift operators.
example:
bit-shift-right
Introduced in: Clarity 2
input: int, uint | uint, uint
output: int | uint
signature: (bit-shift-right i1 shamt)
description:
Shifts all the bits in i1 to the right by the number of places specified in shamt modulo 128 (the bit width of Clarity integers). When i1 is a uint (unsigned), new bits are filled with zeros. When i1 is an int (signed), the sign is preserved, meaning that new bits are filled with the value of the previous sign-bit.
Note that there is a deliberate choice made to ignore arithmetic overflow for this operation. In use cases where overflow should be detected, developers should use *, /, and pow instead of the shift operators.
example:
bit-xor
Introduced in: Clarity 2
input: int, ... | uint, ...
output: int | uint
signature: (bit-xor i1 i2...)
description: Returns the result of bitwise exclusive or'ing a variable number of integer inputs.
example:
buff-to-int-be
Introduced in: Clarity 2
input: (buff 16)
output: int
signature: (buff-to-int-be (buff 16))
description: Converts a byte buffer to a signed integer use a big-endian encoding. The byte buffer can be up to 16 bytes in length. If there are fewer than 16 bytes, as this function uses a big-endian encoding, the input behaves as if it is zero-padded on the left.
Note: This function is only available starting with Stacks 2.1.
example:
buff-to-int-le
Introduced in: Clarity 2
input: (buff 16)
output: int
signature: (buff-to-int-le (buff 16))
description: Converts a byte buffer to a signed integer use a little-endian encoding. The byte buffer can be up to 16 bytes in length. If there are fewer than 16 bytes, as this function uses a little-endian encoding, the input behaves as if it is zero-padded on the right.
Note: This function is only available starting with Stacks 2.1.
example:
buff-to-uint-be
Introduced in: Clarity 2
input: (buff 16)
output: uint
signature: (buff-to-uint-be (buff 16))
description: Converts a byte buffer to an unsigned integer use a big-endian encoding. The byte buffer can be up to 16 bytes in length. If there are fewer than 16 bytes, as this function uses a big-endian encoding, the input behaves as if it is zero-padded on the left.
Note: This function is only available starting with Stacks 2.1.
example:
buff-to-uint-le
Introduced in: Clarity 2
input: (buff 16)
output: uint
signature: (buff-to-uint-le (buff 16))
description: Converts a byte buffer to an unsigned integer use a little-endian encoding. The byte buffer can be up to 16 bytes in length. If there are fewer than 16 bytes, as this function uses a little-endian encoding, the input behaves as if it is zero-padded on the right.
Note: This function is only available starting with Stacks 2.1.
example:
concat
Introduced in: Clarity 1
input: sequence_A, sequence_A
output: sequence_A
signature: (concat sequence1 sequence2)
description:
The concat function takes two sequences of the same type, and returns a concatenated sequence of the same type, with the resulting sequence_len = sequence1_len + sequence2_len. Applicable sequence types are (list A), buff, string-ascii and string-utf8.
example:
contract-call?
Introduced in: Clarity 1
input: ContractName, PublicFunctionName, Arg0, ...
output: (response A B)
signature: (contract-call? .contract-name function-name arg0 arg1 ...)
description:
The contract-call? function executes the given public function of the given contract. You may not use this function to call a public function defined in the current contract. If the public function returns err, any database changes resulting from calling contract-call? are aborted. If the function returns ok, database changes occurred.
example:
contract-hash?
Introduced in: Clarity 4
input: principal
output: (response (buff 32) uint)
signature: (contract-hash? contract)
description: Returns the hash of the specified contract, or an error if the principal is not a contract or the specified contract does not exist. Returns:
(ok 0x<hash>)on success, where<hash>is the SHA-512/256 hash of the code body(err u1)if the principal is not a contract principal.(err u2)if the specified contract does not exist.
example:
contract-of
Introduced in: Clarity 1
input: Trait
output: principal
signature: (contract-of .contract-name)
description:
The contract-of function returns the principal of the contract implementing the trait.
example:
default-to
Introduced in: Clarity 1
input: A, (optional A)
output: A
signature: (default-to default-value option-value)
description:
The default-to function attempts to 'unpack' the second argument: if the argument is a (some ...) option, it returns the inner value of the option. If the second argument is a none value, default-to it returns the value of default-value.
example:
define-constant
Introduced in: Clarity 1
input: MethodSignature, MethodBody
output: Not Applicable
signature: (define-constant name expression)
description:
define-constant is used to define a private constant value in a smart contract. The expression passed into the definition is evaluated at contract launch, in the order that it is supplied in the contract. This can lead to undefined function or undefined variable errors in the event that a function or variable used in the expression has not been defined before the constant.
Like other kinds of definition statements, define-constant may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
example:
define-data-var
Introduced in: Clarity 1
input: VarName, TypeDefinition, Value
output: Not Applicable
signature: (define-data-var var-name type value)
description:
define-data-var is used to define a new persisted variable for use in a smart contract. Such variable are only modifiable by the current smart contract.
Persisted variable are defined with a type and a value.
Like other kinds of definition statements, define-data-var may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
example:
define-fungible-token
Introduced in: Clarity 1
input: TokenName, <uint>
output: Not Applicable
signature: (define-fungible-token token-name <total-supply>)
description:
define-fungible-token is used to define a new fungible token class for use in the current contract.
The second argument, if supplied, defines the total supply of the fungible token. This ensures that all calls to the ft-mint? function will never be able to create more than total-supply tokens. If any such call were to increase the total supply of tokens passed that amount, that invocation of ft-mint? will result in a runtime error and abort.
Like other kinds of definition statements, define-fungible-token may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
Tokens defined using define-fungible-token may be used in ft-transfer?, ft-mint?, and ft-get-balance functions
example:
define-map
Introduced in: Clarity 1
input: MapName, TypeDefinition, TypeDefinition
output: Not Applicable
signature: (define-map map-name key-type value-type)
description:
define-map is used to define a new datamap for use in a smart contract. Such maps are only modifiable by the current smart contract.
Maps are defined with a key type and value type, often these types are tuple types.
Like other kinds of definition statements, define-map may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
example:
define-non-fungible-token
Introduced in: Clarity 1
input: AssetName, TypeSignature
output: Not Applicable
signature: (define-non-fungible-token asset-name asset-identifier-type)
description:
define-non-fungible-token is used to define a new non-fungible token class for use in the current contract. Individual assets are identified by their asset identifier, which must be of the type asset-identifier-type. Asset identifiers are unique identifiers.
Like other kinds of definition statements, define-non-fungible-token may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
Assets defined using define-non-fungible-token may be used in nft-transfer?, nft-mint?, and nft-get-owner? functions
example:
define-private
Introduced in: Clarity 1
input: MethodSignature, MethodBody
output: Not Applicable
signature: (define-private (function-name (arg-name-0 arg-type-0) (arg-name-1 arg-type-1) ...) function-body)
description:
define-private is used to define private functions for a smart contract. Private functions may not be called from other smart contracts, nor may they be invoked directly by users. Instead, these functions may only be invoked by other functions defined in the same smart contract.
Like other kinds of definition statements, define-private may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
Private functions may return any type.
example:
define-public
Introduced in: Clarity 1
input: MethodSignature, MethodBody
output: Not Applicable
signature: (define-public (function-name (arg-name-0 arg-type-0) (arg-name-1 arg-type-1) ...) function-body)
description:
define-public is used to define a public function and transaction for a smart contract. Public functions are callable from other smart contracts and may be invoked directly by users by submitting a transaction to the Stacks blockchain.
Like other kinds of definition statements, define-public may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
Public functions must return a ResponseType (using either ok or err). Any datamap modifications performed by a public function is aborted if the function returns an err type. Public functions may be invoked by other contracts via contract-call?.
example:
define-read-only
Introduced in: Clarity 1
input: MethodSignature, MethodBody
output: Not Applicable
signature: (define-read-only (function-name (arg-name-0 arg-type-0) (arg-name-1 arg-type-1) ...) function-body)
description:
define-read-only is used to define a public read-only function for a smart contract. Such functions are callable from other smart contracts.
Like other kinds of definition statements, define-read-only may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
Read-only functions may return any type. However, read-only functions may not perform any datamap modifications, or call any functions which perform such modifications. This is enforced both during type checks and during the execution of the function. Public read-only functions may be invoked by other contracts via contract-call?.
example:
define-trait
Introduced in: Clarity 1
input: VarName, [MethodSignature]
output: Not Applicable
signature: (define-trait trait-name ((func1-name (arg1-type arg2-type ...) (return-type))))
description:
define-trait is used to define a new trait definition for use in a smart contract. Other contracts can implement a given trait and then have their contract identifier being passed as a function argument in order to be called dynamically with contract-call?.
Traits are defined with a name, and a list of functions, where each function is defined with a name, a list of argument types, and a return type.
In Clarity 1, a trait type can be used to specify the type of a function parameter. A parameter with a trait type can be used as the target of a dynamic contract-call?. A principal literal (e.g. ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM.foo) may be passed as a trait parameter if the specified contract implements all of the functions specified by the trait. A trait value (originating from a parameter with trait type) may also be passed as a trait parameter if the types are the same.
Beginning in Clarity 2, a trait can be used in all of the same ways that a built-in type can be used, except that it cannot be stored in a data var or map, since this would inhibit static analysis. This means that a trait type can be embedded in a compound type (e.g. (optional <my-trait>) or (list 4 <my-trait>)) and a trait value can be bound to a variable in a let or match expression. In addition to the principal literal and trait value with matching type allowed in Clarity 1, Clarity 2 also supports implicit casting from a compatible trait, meaning that a value of type trait-a may be passed to a parameter with type trait-b if trait-a includes all of the requirements of trait-b (and optionally additional functions).
Like other kinds of definition statements, define-trait may only be used at the top level of a smart contract definition (i.e., you cannot put a define statement in the middle of a function body).
example:
element-at
Introduced in: Clarity 1
input: sequence_A, uint
output: (optional A)
signature: (element-at? sequence index)
description:
The element-at? function returns the element at index in the provided sequence. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1).
In Clarity1, element-at must be used (without the ?). The ? is added in Clarity2 for consistency -- built-ins that return responses or optionals end in ?. The Clarity1 spelling is left as an alias in Clarity2 for backwards compatibility.
example:
element-at?
Introduced in: Clarity 2
input: sequence_A, uint
output: (optional A)
signature: (element-at? sequence index)
description:
The element-at? function returns the element at index in the provided sequence. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1).
In Clarity1, element-at must be used (without the ?). The ? is added in Clarity2 for consistency -- built-ins that return responses or optionals end in ?. The Clarity1 spelling is left as an alias in Clarity2 for backwards compatibility.
example:
err
Introduced in: Clarity 1
input: A
output: (response A B)
signature: (err value)
description:
The err function constructs a response type from the input value. Use err for creating return values in public functions. An err value indicates that any database changes during the processing of the function should be rolled back.
example:
filter
Introduced in: Clarity 1
input: Function(A) -> bool, sequence_A
output: sequence_A
signature: (filter func sequence)
description:
The filter function applies the input function func to each element of the input sequence, and returns the same sequence with any elements removed for which func returned false. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1). The func argument must be a literal function name.
example:
fold
Introduced in: Clarity 1
input: Function(A, B) -> B, sequence_A, B
output: B
signature: (fold func sequence_A initial_B)
description:
The fold function condenses sequence_A into a value of type B by recursively applies the function func to each element of the input sequence and the output of a previous application of func.
fold uses initial_B in the initial application of func, along with the first element of sequence_A. The resulting value of type B is used for the next application of func, along with the next element of sequence_A and so on. fold returns the last value of type B returned by these successive applications func.
Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1). The func argument must be a literal function name.
example:
from-consensus-buff?
Introduced in: Clarity 2
input: type-signature(t), buff
output: (optional t)
signature: (from-consensus-buff? type-signature buffer)
description:
from-consensus-buff? is a special function that will deserialize a buffer into a Clarity value, using the SIP-005 serialization of the Clarity value. The type that from-consensus-buff? tries to deserialize into is provided by the first parameter to the function. If it fails to deserialize the type, the method returns none.
example:
ft-burn?
Introduced in: Clarity 1
input: TokenName, uint, principal
output: (response bool uint)
signature: (ft-burn? token-name amount sender)
description:
ft-burn? is used to decrease the token balance for the sender principal for a token type defined using define-fungible-token. The decreased token balance is not transferred to another principal, but rather destroyed, reducing the circulating supply.
On a successful burn, it returns (ok true). The burn may fail with error code:
(err u1)--senderdoes not have enough balance to burn this amount or the amount specified is not positive
example:
ft-get-balance
Introduced in: Clarity 1
input: TokenName, principal
output: uint
signature: (ft-get-balance token-name principal)
description:
ft-get-balance returns token-name balance of the principal principal. The token type must have been defined using define-fungible-token.
example:
ft-get-supply
Introduced in: Clarity 1
input: TokenName
output: uint
signature: (ft-get-supply token-name)
description:
ft-get-balance returns token-name circulating supply. The token type must have been defined using define-fungible-token.
example:
ft-mint?
Introduced in: Clarity 1
input: TokenName, uint, principal
output: (response bool uint)
signature: (ft-mint? token-name amount recipient)
description:
ft-mint? is used to increase the token balance for the recipient principal for a token type defined using define-fungible-token. The increased token balance is not transferred from another principal, but rather minted.
If a non-positive amount is provided to mint, this function returns (err 1). Otherwise, on successfully mint, it returns (ok true). If this call would result in more supplied tokens than defined by the total supply in define-fungible-token, then a SupplyOverflow runtime error is thrown.
example:
ft-transfer?
Introduced in: Clarity 1
input: TokenName, uint, principal, principal
output: (response bool uint)
signature: (ft-transfer? token-name amount sender recipient)
description:
ft-transfer? is used to increase the token balance for the recipient principal for a token type defined using define-fungible-token by debiting the sender principal. In contrast to stx-transfer?, any user can transfer the assets. When used, relevant guards need to be added.
This function returns (ok true) if the transfer is successful. In the event of an unsuccessful transfer it returns one of the following error codes:
(err u1)--senderdoes not have enough balance to transfer(err u2)--senderandrecipientare the same principal(err u3)-- amount to send is non-positive
example:
get
Introduced in: Clarity 1
input: KeyName, (tuple) | (optional (tuple))
output: A
signature: (get key-name tuple)
description:
The get function fetches the value associated with a given key from the supplied typed tuple. If an Optional value is supplied as the inputted tuple, get returns an Optional type of the specified key in the tuple. If the supplied option is a none option, get returns none.
example:
get-block-info?
Deprecated in Clarity 3.
Introduced in: Clarity 1
input: BlockInfoPropertyName, uint
output: (optional buff) | (optional uint)
signature: (get-block-info? prop-name block-height)
description:
In Clarity 3, get-block-info? is removed. In its place, get-stacks-block-info? can be used to retrieve information about a Stacks block and get-tenure-info? can be used to get information pertaining to the tenure.
The get-block-info? function fetches data for a block of the given Stacks block height. The value and type returned are determined by the specified BlockInfoPropertyName. If the provided block-height does not correspond to an existing block prior to the current block, the function returns none. The currently available property names are as follows:
burnchain-header-hash: This property returns a(buff 32)value containing the header hash of the burnchain (Bitcoin) block that selected the Stacks block at the given Stacks chain height.id-header-hash: This property returns a(buff 32)value containing the index block hash of a Stacks block. This hash is globally unique, and is derived from the block hash and the history of accepted PoX operations. This is also the block hash value you would pass into(at-block).header-hash: This property returns a(buff 32)value containing the header hash of a Stacks block, given a Stacks chain height. *WARNING this hash is not guaranteed to be globally unique, since the same Stacks block can be mined in different PoX forks. If you need global uniqueness, you should useid-header-hash.miner-address: This property returns aprincipalvalue corresponding to the miner of the given block. WARNING In Stacks 2.1, this is not guaranteed to be the sameprincipalthat received the block reward, since Stacks 2.1 supports coinbase transactions that pay the reward to a contract address. This is merely the address of theprincipalthat produced the block.time: This property returns auintvalue of the block header time field. This is a Unix epoch timestamp in seconds which roughly corresponds to when the block was mined. This timestamp comes from the burnchain block. Note: this does not increase monotonically with each block and block times are accurate only to within two hours. See BIP113 for more information. For blocks mined after epoch 3.0, all Stacks blocks in one tenure will share the same timestamp. To get the Stacks block time for a block in epoch 3.0+, useget-stacks-block-info?.vrf-seed: This property returns a(buff 32)value of the VRF seed for the corresponding block.block-reward: This property returns auintvalue for the total block reward of the indicated Stacks block. This value is only available once the reward for the block matures. That is, the latestblock-rewardvalue available is at least 101 Stacks blocks in the past (on mainnet). The reward includes the coinbase, the anchored block's transaction fees, and the shares of the confirmed and produced microblock transaction fees earned by this block's miner. Note that this value may be smaller than the Stacks coinbase at this height, because the miner may have been punished with a validPoisonMicroblocktransaction in the event that the miner published two or more microblock stream forks. Added in Clarity 2.miner-spend-total: This property returns auintvalue for the total number of burnchain tokens (i.e. satoshis) spent by all miners trying to win this block. Added in Clarity 2.miner-spend-winner: This property returns auintvalue for the number of burnchain tokens (i.e. satoshis) spent by the winning miner for this Stacks block. Note that this value is less than or equal to the value forminer-spend-totalat the same block height. Added in Clarity 2.
example:
get-burn-block-info?
Introduced in: Clarity 2
input: BurnBlockInfoPropertyName, uint
output: (optional buff) | (optional (tuple (addrs (list 2 (tuple (hashbytes (buff 32)) (version (buff 1))))) (payout uint)))
signature: (get-burn-block-info? prop-name burn-block-height)
description:
The get-burn-block-info? function fetches data for a block of the given burnchain block height. The value and type returned are determined by the specified BlockInfoPropertyName. Valid values for burn-block-height only include heights between the burnchain height at the time the Stacks chain was launched, and the last-processed burnchain block. If the burn-block-height argument falls outside of this range, then none shall be returned.
The following BlockInfoPropertyName values are defined:
The
header-hashproperty returns a 32-byte buffer representing the header hash of the burnchain block at burnchain heightburn-block-height.The
pox-addrsproperty returns a tuple with two items: a list of up to two PoX addresses that received a PoX payout at that block height, and the amount of burnchain tokens paid to each address (note that per the blockchain consensus rules, each PoX payout will be the same for each address in the block-commit transaction). The list will include burn addresses -- that is, the unspendable addresses that miners pay to when there are no PoX addresses left to be paid. During the prepare phase, there will be exactly one burn address reported. During the reward phase, up to two burn addresses may be reported in the event that some PoX reward slots are not claimed.
The addrs list contains the same PoX address values passed into the PoX smart contract:
They each have type signature
(tuple (hashbytes (buff 32)) (version (buff 1)))The
versionfield can be any of the following:0x00means this is a p2pkh address, andhashbytesis the 20-byte hash160 of a single public key0x01means this is a p2sh address, andhashbytesis the 20-byte hash160 of a redeemScript script0x02means this is a p2wpkh-p2sh address, andhashbytesis the 20-byte hash160 of a p2wpkh witness script0x03means this is a p2wsh-p2sh address, andhashbytesis the 20-byte hash160 of a p2wsh witness script0x04means this is a p2wpkh address, andhashbytesis the 20-byte hash160 of the witness script0x05means this is a p2wsh address, andhashbytesis the 32-byte sha256 of the witness script0x06means this is a p2tr address, andhashbytesis the 32-byte sha256 of the witness script
example:
get-stacks-block-info?
Introduced in: Clarity 3
input: StacksBlockInfoPropertyName, uint
output: (optional buff) | (optional uint)
signature: (get-stacks-block-info? prop-name stacks-block-height)
description:
The get-stacks-block-info? function fetches data for a block of the given Stacks block height. The value and type returned are determined by the specified StacksBlockInfoPropertyName. If the provided stacks-block-height does not correspond to an existing block prior to the current block, the function returns none. The currently available property names are as follows:
id-header-hash: This property returns a(buff 32)value containing the index block hash of a Stacks block. This hash is globally unique, and is derived from the block hash and the history of accepted PoX operations. This is also the block hash value you would pass into(at-block).header-hash: This property returns a(buff 32)value containing the header hash of a Stacks block, given a Stacks chain height. *WARNING this hash is not guaranteed to be globally unique, since the same Stacks block can be mined in different PoX forks. If you need global uniqueness, you should useid-header-hash.time: This property returns auintvalue of the block header time field. This is a Unix epoch timestamp in seconds which roughly corresponds to when the block was mined. For a block mined before epoch 3.0, this timestamp comes from the burnchain block. Note: this does not increase monotonically with each block and block times are accurate only to within two hours. See BIP113 for more information. For a block mined after epoch 3.0, this timestamp comes from the Stacks block header. Note: this is the time, according to the miner, when the mining of this block started, but is not guaranteed to be accurate. This time will be validated by the signers to be:Greater than the timestamp of the previous block
At most 15 seconds into the future (according to their own local clocks)
example:
get-tenure-info?
Introduced in: Clarity 3
input: TenureInfoPropertyName, uint
output: (optional buff) | (optional uint)
signature: (get-tenure-info? prop-name stacks-block-height)
description:
The get-tenure-info? function fetches data for the tenure at the given block height. The value and type returned are determined by the specified TenureInfoPropertyName. If the provided stacks-block-height does not correspond to an existing block prior to the current block, the function returns none. The currently available property names are as follows:
burnchain-header-hash: This property returns a(buff 32)value containing the header hash of the burnchain (Bitcoin) block that selected the tenure at the given height.miner-address: This property returns aprincipalvalue corresponding to the miner of the given tenure. WARNING This is not guaranteed to be the sameprincipalthat received the block reward, since Stacks 2.1+ supports coinbase transactions that pay the reward to a contract address. This is merely the address of theprincipalthat produced the tenure.time: This property returns auintUnix epoch timestamp in seconds which roughly corresponds to when the tenure was started. This timestamp comes from the burnchain block. Note: this does not increase monotonically with each tenure and tenure times are accurate only to within two hours. See BIP113 for more information.vrf-seed: This property returns a(buff 32)value of the VRF seed for the corresponding tenure.block-reward: This property returns auintvalue for the total block reward of the indicated tenure. This value is only available once the reward for the tenure matures. That is, the latestblock-rewardvalue available is at least 101 Stacks blocks in the past (on mainnet). The reward includes the coinbase, the anchored tenure's transaction fees, and the shares of the confirmed and produced microblock transaction fees earned by this block's miner. Note that this value may be smaller than the Stacks coinbase at this height, because the miner may have been punished with a validPoisonMicroblocktransaction in the event that the miner published two or more microblock stream forks.miner-spend-total: This property returns auintvalue for the total number of burnchain tokens (i.e. satoshis) spent by all miners trying to win this tenure.miner-spend-winner: This property returns auintvalue for the number of burnchain tokens (i.e. satoshis) spent by the winning miner for this tennure. Note that this value is less than or equal to the value forminer-spend-totalat the same tenure height.
example:
hash160
Introduced in: Clarity 1
input: buff|uint|int
output: (buff 20)
signature: (hash160 value)
description:
The hash160 function computes RIPEMD160(SHA256(x)) of the inputted value. If an integer (128 bit) is supplied the hash is computed over the little-endian representation of the integer.
example:
if
Introduced in: Clarity 1
input: bool, A, A
output: A
signature: (if bool1 expr1 expr2)
description:
The if function admits a boolean argument and two expressions which must return the same type. In the case that the boolean input is true, the if function evaluates and returns expr1. If the boolean input is false, the if function evaluates and returns expr2.
example:
impl-trait
Introduced in: Clarity 1
input: TraitIdentifier
output: Not Applicable
signature: (impl-trait trait-identifier)
description:
impl-trait can be use for asserting that a contract is fully implementing a given trait. Additional checks are being performed when the contract is being published, rejecting the deployment if the contract is violating the trait specification.
Trait identifiers can either be using the sugared syntax (.token-a.token-trait), or be fully qualified ('SPAXYA5XS51713FDTQ8H94EJ4V579CXMTRNBZKSF.token-a.token-trait).
Like other kinds of definition statements, impl-trait may only be used at the top level of a smart contract definition (i.e., you cannot put such a statement in the middle of a function body).
example:
index-of
Introduced in: Clarity 1
input: sequence_A, A
output: (optional uint)
signature: (index-of? sequence item)
description:
The index-of? function returns the first index at which item can be found, using is-eq checks, in the provided sequence. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1). If the target item is not found in the sequence (or if an empty string or buffer is supplied), this function returns none.
In Clarity1, index-of must be used (without the ?). The ? is added in Clarity2 for consistency -- built-ins that return responses or optionals end in ?. The Clarity1 spelling is left as an alias in Clarity2 for backwards compatibility.
example:
index-of?
Introduced in: Clarity 2
input: sequence_A, A
output: (optional uint)
signature: (index-of? sequence item)
description:
The index-of? function returns the first index at which item can be found, using is-eq checks, in the provided sequence. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1). If the target item is not found in the sequence (or if an empty string or buffer is supplied), this function returns none.
In Clarity1, index-of must be used (without the ?). The ? is added in Clarity2 for consistency -- built-ins that return responses or optionals end in ?. The Clarity1 spelling is left as an alias in Clarity2 for backwards compatibility.
example:
int-to-ascii
Introduced in: Clarity 2
input: int | uint
output: (string-ascii 40)
signature: (int-to-ascii (int|uint))
description:
Converts an integer, either int or uint, to a string-ascii string-value representation.
Note: This function is only available starting with Stacks 2.1.
example:
int-to-utf8
Introduced in: Clarity 2
input: int | uint
output: (string-utf8 40)
signature: (int-to-utf8 (int|uint))
description:
Converts an integer, either int or uint, to a string-utf8 string-value representation.
Note: This function is only available starting with Stacks 2.1.
example:
is-eq
Introduced in: Clarity 1
input: A, A, ...
output: bool
signature: (is-eq v1 v2...)
description:
Compares the inputted values, returning true if they are all equal. Note that unlike the (and ...) function, (is-eq ...) will not short-circuit. All values supplied to is-eq must be the same type.
example:
is-err
Introduced in: Clarity 1
input: (response A B)
output: bool
signature: (is-err value)
description:
is-err tests a supplied response value, returning true if the response was an err, and false if it was an ok.
example:
is-none
Introduced in: Clarity 1
input: (optional A)
output: bool
signature: (is-none value)
description:
is-none tests a supplied option value, returning true if the option value is none, and false if it is a (some ...).
example:
is-ok
Introduced in: Clarity 1
input: (response A B)
output: bool
signature: (is-ok value)
description:
is-ok tests a supplied response value, returning true if the response was ok, and false if it was an err.
example:
is-some
Introduced in: Clarity 1
input: (optional A)
output: bool
signature: (is-some value)
description:
is-some tests a supplied option value, returning true if the option value is (some ...), and false if it is a none.
example:
is-standard
Introduced in: Clarity 2
input: principal
output: bool
signature: (is-standard standard-or-contract-principal)
description:
Tests whether standard-or-contract-principal matches the current network type, and therefore represents a principal that can spend tokens on the current network type. That is, the network is either of type mainnet, or testnet. Only SPxxxx and SMxxxx c32check form addresses can spend tokens on a mainnet, whereas only STxxxx and SNxxxx c32check forms addresses can spend tokens on a testnet. All addresses can receive tokens, but only principal c32check form addresses that match the network type can spend tokens on the network. This method will return true if and only if the principal matches the network type, and false otherwise.
Note: This function is only available starting with Stacks 2.1.
example:
keccak256
Introduced in: Clarity 1
input: buff|uint|int
output: (buff 32)
signature: (keccak256 value)
description:
The keccak256 function computes KECCAK256(value) of the inputted value.
Note: this differs from the NIST SHA-3 (that is, FIPS 202) standard. If an integer (128 bit) is supplied the hash is computed over the little-endian representation of the integer.
example:
len
Introduced in: Clarity 1
input: sequence_A
output: uint
signature: (len sequence)
description:
The len function returns the length of a given sequence. Applicable sequence types are (list A), buff, string-ascii and string-utf8.
example:
let
Introduced in: Clarity 1
input: ((name1 AnyType) (name2 AnyType) ...), AnyType, ... A
output: A
signature: (let ((name1 expr1) (name2 expr2) ...) expr-body1 expr-body2 ... expr-body-last)
description:
The let function accepts a list of variable name and expression pairs, evaluating each expression and binding it to the corresponding variable name. let bindings are sequential: when a let binding is evaluated, it may refer to prior binding. The context created by this set of bindings is used for evaluating its body expressions. The let expression returns the value of the last such body expression.
Note: intermediary statements returning a response type must be checked
example:
list
Introduced in: Clarity 1
input: A, ...
output: (list A)
signature: (list expr1 expr2 expr3 ...)
description:
The list function constructs a list composed of the inputted values. Each supplied value must be of the same type.
example:
log2
Introduced in: Clarity 1
input: int | uint
output: int | uint
signature: (log2 n)
description:
Returns the power to which the number 2 must be raised to obtain the value n, rounded down to the nearest integer. Fails on a negative numbers.
example:
map
Introduced in: Clarity 1
input: Function(A, B, ..., N) -> X, sequence_A, sequence_B, ..., sequence_N
output: (list X)
signature: (map func sequence_A sequence_B ... sequence_N)
description:
The map function applies the function func to each corresponding element of the input sequences, and outputs a list of the same type containing the outputs from those function applications. Applicable sequence types are (list A), buff, string-ascii and string-utf8, for which the corresponding element types are, respectively, A, (buff 1), (string-ascii 1) and (string-utf8 1). The func argument must be a literal function name.
Note: no matter what kind of sequences the inputs are, the output is always a list.
example:
map-delete
Introduced in: Clarity 1
input: MapName, tuple
output: bool
signature: (map-delete map-name key-tuple)
description:
The map-delete function removes the value associated with the input key for the given map. If an item exists and is removed, the function returns true. If a value did not exist for this key in the data map, the function returns false.
example:
map-get?
Introduced in: Clarity 1
input: MapName, tuple
output: (optional (tuple))
signature: (map-get? map-name key-tuple)
description:
The map-get? function looks up and returns an entry from a contract's data map. The value is looked up using key-tuple. If there is no value associated with that key in the data map, the function returns a none option. Otherwise, it returns (some value).
example:
map-insert
Introduced in: Clarity 1
input: MapName, tuple_A, tuple_B
output: bool
signature: (map-insert map-name key-tuple value-tuple)
description:
The map-insert function sets the value associated with the input key to the inputted value if and only if there is not already a value associated with the key in the map. If an insert occurs, the function returns true. If a value already existed for this key in the data map, the function returns false.
Note: the value-tuple requires 1 additional byte for storage in the materialized blockchain state, and therefore the maximum size of a value that may be inserted into a map is MAX_CLARITY_VALUE - 1.
example:
map-set
Introduced in: Clarity 1
input: MapName, tuple_A, tuple_B
output: bool
signature: (map-set map-name key-tuple value-tuple)
description:
The map-set function sets the value associated with the input key to the inputted value. This function performs a blind update; whether or not a value is already associated with the key, the function overwrites that existing association.
Note: the value-tuple requires 1 additional byte for storage in the materialized blockchain state, and therefore the maximum size of a value that may be inserted into a map is MAX_CLARITY_VALUE - 1.
example:
match
Introduced in: Clarity 1
input: (optional A) name expression expression | (response A B) name expression name expression
output: C
signature: (match opt-input some-binding-name some-branch none-branch) | (match-resp input ok-binding-name ok-branch err-binding-name err-branch)
description:
The match function is used to test and destructure optional and response types.
If the input is an optional, it tests whether the provided input is a some or none option, and evaluates some-branch or none-branch in each respective case.
Within the some-branch, the contained value of the input argument is bound to the provided some-binding-name name.
Only one of the branches will be evaluated (similar to if statements).
If the input is a response, it tests whether the provided input is an ok or err response type, and evaluates ok-branch or err-branch in each respective case.
Within the ok-branch, the contained ok value of the input argument is bound to the provided ok-binding-name name.
Within the err-branch, the contained err value of the input argument is bound to the provided err-binding-name name.
Only one of the branches will be evaluated (similar to if statements).
Note: Type checking requires that the type of both the ok and err parts of the response object be determinable. For situations in which one of the parts of a response is untyped, you should use unwrap-panic or unwrap-err-panic instead of match.
example:
merge
Introduced in: Clarity 1
input: tuple, tuple
output: tuple
signature: (merge tuple { key1: val1 })
description:
The merge function returns a new tuple with the combined fields, without mutating the supplied tuples.
example:
mod
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: int | uint
signature: (mod i1 i2)
description:
Returns the integer remainder from integer dividing i1 by i2. In the event of a division by zero, throws a runtime error.
example:
nft-burn?
Introduced in: Clarity 1
input: AssetName, A, principal
output: (response bool uint)
signature: (nft-burn? asset-class asset-identifier sender)
description:
nft-burn? is used to burn an asset that the sender principal owns. The asset must have been defined using define-non-fungible-token, and the supplied asset-identifier must be of the same type specified in that definition.
On a successful burn, it returns (ok true). In the event of an unsuccessful burn it returns one of the following error codes:
(err u1)--senderdoes not own the specified asset(err u3)-- the asset specified byasset-identifierdoes not exist
example:
nft-get-owner?
Introduced in: Clarity 1
input: AssetName, A
output: (optional principal)
signature: (nft-get-owner? asset-class asset-identifier)
description:
nft-get-owner? returns the owner of an asset, identified by asset-identifier, or none if the asset does not exist. The asset type must have been defined using define-non-fungible-token, and the supplied asset-identifier must be of the same type specified in that definition.
example:
nft-mint?
Introduced in: Clarity 1
input: AssetName, A, principal
output: (response bool uint)
signature: (nft-mint? asset-class asset-identifier recipient)
description:
nft-mint? is used to instantiate an asset and set that asset's owner to the recipient principal. The asset must have been defined using define-non-fungible-token, and the supplied asset-identifier must be of the same type specified in that definition.
The function returns (ok true) if the mint is successful. This function may fail with the error code:
(err u1)-- an asset identified byasset-identifieralready exists
example:
nft-transfer?
Introduced in: Clarity 1
input: AssetName, A, principal, principal
output: (response bool uint)
signature: (nft-transfer? asset-class asset-identifier sender recipient)
description:
nft-transfer? is used to change the owner of an asset identified by asset-identifier from sender to recipient. The asset-class must have been defined by define-non-fungible-token and asset-identifier must be of the type specified in that definition. In contrast to stx-transfer?, any user can transfer the asset. When used, relevant guards need to be added.
This function returns (ok true) if the transfer is successful. In the event of an unsuccessful transfer it returns one of the following error codes:
(err u1)--senderdoes not own the asset(err u2)--senderandrecipientare the same principal(err u3)-- asset identified by asset-identifier does not exist
example:
not
Introduced in: Clarity 1
input: bool
output: bool
signature: (not b1)
description: Returns the inverse of the boolean input.
example:
ok
Introduced in: Clarity 1
input: A
output: (response A B)
signature: (ok value)
description:
The ok function constructs a response type from the input value. Use ok for creating return values in public functions. An ok value indicates that any database changes during the processing of the function should materialize.
example:
or
Introduced in: Clarity 1
input: bool, ...
output: bool
signature: (or b1 b2 ...)
description:
Returns true if any boolean inputs are true. Importantly, the supplied arguments are evaluated in-order and lazily. Lazy evaluation means that if one of the arguments returns true, the function short-circuits, and no subsequent arguments are evaluated.
example:
pow
Introduced in: Clarity 1
input: int, int | uint, uint | string-ascii, string-ascii | string-utf8, string-utf8 | buff, buff
output: int | uint
signature: (pow i1 i2)
description:
Returns the result of raising i1 to the power of i2. In the event of an overflow, throws a runtime error. Note: Corner cases are handled with the following rules:
if both
i1andi2are0, return1if
i1is1, return1if
i1is0, return0if
i2is negative or greater thanu32::MAX, throw a runtime error
example:
principal-construct?
Introduced in: Clarity 2
input: (buff 1), (buff 20), [(string-ascii 40)]
output: (response principal { error_code: uint, value: (optional principal) })
signature: (principal-construct? (buff 1) (buff 20) [(string-ascii 40)])
description:
A principal value represents either a set of keys, or a smart contract. The former, called a standard principal, is encoded as a (buff 1) version byte, indicating the type of account and the type of network that this principal can spend tokens on, and a (buff 20) public key hash, characterizing the principal's unique identity. The latter, a contract principal, is encoded as a standard principal concatenated with a (string-ascii 40) contract name that identifies the code body.
The principal-construct? function allows users to create either standard or contract principals, depending on which form is used. To create a standard principal, principal-construct? would be called with two arguments: it takes as input a (buff 1) which encodes the principal address's version-byte, a (buff 20) which encodes the principal address's hash-bytes. To create a contract principal, principal-construct? would be called with three arguments: the (buff 1) and (buff 20) to represent the standard principal that created the contract, and a (string-ascii 40) which encodes the contract's name. On success, this function returns either a standard principal or contract principal, depending on whether or not the third (string-ascii 40) argument is given.
This function returns a Response. On success, the ok value is a Principal. The err value is a value tuple with the form { error_code: uint, value: (optional principal) }.
If the single-byte version-byte is in the valid range 0x00 to 0x1f, but is not an appropriate version byte for the current network, then the error will be u0, and value will contain (some principal), where the wrapped value is the principal. If the version-byte is not in this range, however, then the value will be none.
If the version-byte is a buff of length 0, if the single-byte version-byte is a value greater than 0x1f, or the hash-bytes is a buff of length not equal to 20, then error_code will be u1 and value will be none.
If a name is given, and the name is either an empty string or contains ASCII characters that are not allowed in contract names, then error_code will be u2.
Note: This function is only available starting with Stacks 2.1.
example:
principal-destruct?
Introduced in: Clarity 2
input: principal
output: (response (tuple (hash-bytes (buff 20)) (name (optional (string-ascii 40))) (version (buff 1))) (tuple (hash-bytes (buff 20)) (name (optional (string-ascii 40))) (version (buff 1))))
signature: (principal-destruct? principal-address)
description:
A principal value represents either a set of keys, or a smart contract. The former, called a standard principal, is encoded as a (buff 1) version byte, indicating the type of account and the type of network that this principal can spend tokens on, and a (buff 20) public key hash, characterizing the principal's unique identity. The latter, a contract principal, is encoded as a standard principal concatenated with a (string-ascii 40) contract name that identifies the code body.
principal-destruct? will decompose a principal into its component parts: either{version-byte, hash-bytes} for standard principals, or {version-byte, hash-bytes, name} for contract principals.
This method returns a Response that wraps this data as a tuple.
If the version byte of principal-address matches the network (see is-standard), then this method returns the pair as its ok value.
If the version byte of principal-address does not match the network, then this method returns the pair as its err value.
In both cases, the value itself is a tuple containing three fields: a version value as a (buff 1), a hash-bytes value as a (buff 20), and a name value as an (optional (string-ascii 40)). The name field will only be (some ..) if the principal is a contract principal.
Note: This function is only available starting with Stacks 2.1.
example:
principal-of?
Introduced in: Clarity 1
input: (buff 33)
output: (response principal uint)
signature: (principal-of? public-key)
description:
The principal-of? function returns the principal derived from the provided public key. This function may fail with the error code:
(err u1)--public-keyis invalid
Note: Before Stacks 2.1, this function has a bug, in that the principal returned would always be a testnet single-signature principal, even if the function were run on the mainnet. Starting with Stacks 2.1, this bug is fixed, so that this function will return a principal suited to the network it is called on. In particular, if this is called on the mainnet, it will return a single-signature mainnet principal.
example:
print
Introduced in: Clarity 1
input: A
output: A
signature: (print expr)
description:
The print function evaluates and returns its input expression. On Stacks Core nodes configured for development (as opposed to production mining nodes), this function prints the resulting value to STDOUT (standard output).
example:
replace-at?
Introduced in: Clarity 2
input: sequence_A, uint, A
output: (optional sequence_A)
signature: (replace-at? sequence index element)
description:
The replace-at? function takes in a sequence, an index, and an element, and returns a new sequence with the data at the index position replaced with the given element. The given element's type must match the type of the sequence, and must correspond to a single index of the input sequence. The return type on success is the same type as the input sequence.
If the provided index is out of bounds, this functions returns none.
example:
restrict-assets?
Introduced in: Clarity 4
input: principal, ((Allowance){0,128}), AnyType, ... A
output: (response A int)
signature: (restrict-assets? asset-owner ((with-stx|with-ft|with-nft|with-stacking)*) expr-body1 expr-body2 ... expr-body-last)
description:
Executes the body expressions, then checks the asset outflows against the granted allowances, in declaration order. If any allowance is violated, the body expressions are reverted, an error is returned, and an event is emitted with the full details of the violation to help with debugging. Note that the asset-owner and allowance setup expressions are evaluated before executing the body expressions. The final body expression cannot return a response value in order to avoid returning a nested response value from restrict-assets? (nested responses are error-prone). Returns:
(ok x)if the outflows are within the allowances, wherexis the result of the final body expression and has typeA.(err index)if an allowance was violated, whereindexis the 0-based index of the first violated allowance in the list of granted allowances, oru128if an asset with no allowance caused the violation.
example:
secp256k1-recover?
Introduced in: Clarity 1
input: (buff 32), (buff 65)
output: (response (buff 33) uint)
signature: (secp256k1-recover? message-hash signature)
description:
The secp256k1-recover? function recovers the public key used to sign the hash, message-hash, typically a sha256 hash, with the provided signature. The signature includes 64 bytes plus an additional recovery id (00..03) for a total of 65 bytes. On success, it returns the public key as a 33-byte buffer. This function may fail with one of the following error codes:
(err u1)- the signature does not match the message hash(err u2)- the signature is invalid
example:
secp256k1-verify
Introduced in: Clarity 1
input: (buff 32), (buff 64) | (buff 65), (buff 33)
output: bool
signature: (secp256k1-verify message-hash signature public-key)
description:
The secp256k1-verify function verifies that the provided signature of the message-hash was signed with the private key that generated the public key. The message-hash is typically the sha256 of a message. The signature includes 64 bytes plus an optional additional recovery id (00..03) for a total of 64 or 65 bytes. High-S signatures are rejected to enforce the canonical low-S form and prevent malleable signatures.
example:
secp256r1-verify
Introduced in: Clarity 4
input: (buff 32), (buff 64), (buff 33)
output: bool
signature: (secp256r1-verify message-hash signature public-key)
description:
The secp256r1-verify function verifies that the provided signature of the message-hash was signed with the private key that generated the public key. In Clarity 4, the message-hash is SHA256 hashed again internally before verification (i.e. double SHA256) but in Clarity 5 and later, the message-hash is used directly without additional hashing. message-hash is typically the sha256 of a message and signature is the raw 64-byte signature. High-S signatures are allowed. Note that this is NOT the Bitcoin (or default Stacks) signature scheme, secp256k1, but rather the NIST P-256 curve (also known as secp256r1).
example:
sha256
Introduced in: Clarity 1
input: buff|uint|int
output: (buff 32)
signature: (sha256 value)
description:
The sha256 function computes SHA256(x) of the inputted value. If an integer (128 bit) is supplied the hash is computed over the little-endian representation of the integer.
example:
sha512
Introduced in: Clarity 1
input: buff|uint|int
output: (buff 64)
signature: (sha512 value)
description:
The sha512 function computes SHA512(x) of the inputted value. If an integer (128 bit) is supplied the hash is computed over the little-endian representation of the integer.
example:
sha512/256
Introduced in: Clarity 1
input: buff|uint|int
output: (buff 32)
signature: (sha512/256 value)
description:
The sha512/256 function computes SHA512/256(x) (the SHA512 algorithm with the 512/256 initialization vector, truncated to 256 bits) of the inputted value. If an integer (128 bit) is supplied the hash is computed over the little-endian representation of the integer.
example:
slice?
Introduced in: Clarity 2
input: sequence_A, uint, uint
output: (optional sequence_A)
signature: (slice? sequence left-position right-position)
description:
The slice? function attempts to return a sub-sequence of that starts at left-position (inclusive), and ends at right-position (non-inclusive). If left_position==right_position, the function returns an empty sequence. If either left_position or right_position are out of bounds OR if right_position is less than left_position, the function returns none.
example:
some
Introduced in: Clarity 1
input: A
output: (optional A)
signature: (some value)
description:
The some function constructs a optional type from the input value.
example:
sqrti
Introduced in: Clarity 1
input: int | uint
output: int | uint
signature: (sqrti n)
description:
Returns the largest integer that is less than or equal to the square root of n. Fails on a negative numbers.
example:
string-to-int?
Introduced in: Clarity 2
input: (string-ascii 1048576) | (string-utf8 262144)
output: (optional int)
signature: (string-to-int? (string-ascii|string-utf8))
description:
Converts a string, either string-ascii or string-utf8, to an optional-wrapped signed integer. If the input string does not represent a valid integer, then the function returns none. Otherwise it returns an integer wrapped in some.
Note: This function is only available starting with Stacks 2.1.
example:
string-to-uint?
Introduced in: Clarity 2
input: (string-ascii 1048576) | (string-utf8 262144)
output: (optional uint)
signature: (string-to-uint? (string-ascii|string-utf8))
description:
Converts a string, either string-ascii or string-utf8, to an optional-wrapped unsigned integer. If the input string does not represent a valid integer, then the function returns none. Otherwise it returns an unsigned integer wrapped in some.
Note: This function is only available starting with Stacks 2.1.
example:
stx-account
Introduced in: Clarity 2
input: principal
output: (tuple (locked uint) (unlock-height uint) (unlocked uint))
signature: (stx-account owner)
description:
stx-account is used to query the STX account of the owner principal.
This function returns a tuple with the canonical account representation for an STX account. This includes the current amount of unlocked STX, the current amount of locked STX, and the unlock height for any locked STX, all denominated in microstacks.
example:
stx-burn?
Introduced in: Clarity 1
input: uint, principal
output: (response bool uint)
signature: (stx-burn? amount sender)
description:
stx-burn? decreases the sender principal's STX holdings by amount, specified in microstacks, by destroying the STX. The sender principal must be equal to the current context's tx-sender.
This function returns (ok true) if the burn is successful. In the event of an unsuccessful burn it returns one of the following error codes:
(err u1)--senderdoes not have enough balance to burn(err u3)-- amount to burn is non-positive(err u4)-- thesenderprincipal is not the currenttx-sender
example:
stx-get-balance
Introduced in: Clarity 1
input: principal
output: uint
signature: (stx-get-balance owner)
description:
stx-get-balance is used to query the STX balance of the owner principal.
This function returns the (unlocked) STX balance, in microstacks (1 STX = 1,000,000 microstacks), of the owner principal. The result is the same as (get unlocked (stx-account user)). In the event that the owner principal isn't materialized, it returns 0.
example:
stx-transfer-memo?
Introduced in: Clarity 2
input: uint, principal, principal, buff
output: (response bool uint)
signature: (stx-transfer-memo? amount sender recipient memo)
description:
stx-transfer-memo? is similar to stx-transfer?, except that it adds a memo field.
This function returns (ok true) if the transfer is successful, or, on an error, returns the same codes as stx-transfer?.
example:
stx-transfer?
Introduced in: Clarity 1
input: uint, principal, principal, buff
output: (response bool uint)
signature: (stx-transfer? amount sender recipient)
description:
stx-transfer? is used to increase the STX balance for the recipient principal by debiting the sender principal by amount, specified in microstacks. The sender principal must be equal to the current context's tx-sender.
This function returns (ok true) if the transfer is successful. In the event of an unsuccessful transfer it returns one of the following error codes:
(err u1)--senderdoes not have enough balance to transfer(err u2)--senderandrecipientare the same principal(err u3)-- amount to send is non-positive(err u4)-- thesenderprincipal is not the currenttx-sender
example:
to-ascii?
Introduced in: Clarity 4
input: int|uint|bool|principal|(buff 524284)|(string-utf8 1048571)
output: (response (string-ascii 1048571) uint)
signature: (to-ascii? value)
description:
The to-ascii? function converts the input value to its ASCII representation. If the input is a string-utf8, it will fail with (err u1) if the string contains non-ASCII characters.
example:
to-consensus-buff?
Introduced in: Clarity 2
input: any
output: (optional buff)
signature: (to-consensus-buff? value)
description:
to-consensus-buff? is a special function that will serialize any Clarity value into a buffer, using the SIP-005 serialization of the Clarity value. Not all values can be serialized: some value's consensus serialization is too large to fit in a Clarity buffer (this is because of the type prefix in the consensus serialization).
If the value cannot fit as serialized into the maximum buffer size, this returns none, otherwise, it will be (some consensus-serialized-buffer). During type checking, the analyzed type of the result of this method will be the maximum possible consensus buffer length based on the inferred type of the supplied value.
example:
to-int
Introduced in: Clarity 1