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# [Ride v5] Built-in variables

⚠️ This is the documentation for the Standard library version 5. We recommend to use version 6. Go to version 6

A built-in variable is a variable of the Standard library.

Name Description
Buy Order type
  • CEILING
  • DOWN
  • FLOOR
  • HALFEVEN
  • HALFUP
 Rounding methods used in the math functions fraction, log, pow
height Blockchain height at the script execution time
lastBlock Information about the last block of the blockchain at the script execution time
nil Variable that contains an empty list.
The variable is used for creating lists. For example, instead of:

    let a = [5,6]
you can write: 

    let b = 5::6::nil
Lists are created using both methods. The first method is a syntactic sugar
  • NOALG
  • MD5
  • SHA1
  • SHA224
  • SHA256
  • SHA384
  • SHA512
  • SHA3224
  • SHA3256
  • SHA3384
  • SHA3512
 Variables that are passed as the first parameter to the rsaVerify function
Sell Order type
this • For a dApp script or an account script: the Address structure
• For an asset script: the Asset structure
tx Transaction or order
unit Variable that contains an object of Unit type.
Example 1
the deposit function transfers 5 WAVELETs to the account, that called this function. 

{-# STDLIB_VERSION 5 #-}
{-# CONTENT_TYPE DAPP #-}
{-# SCRIPT_TYPE ACCOUNT #-}

@Callable(inv)
func deposit() = {
  (
    [
      # Transfer 5 WAVELETs to the inv.caller account
      # WAVES does not have a token ID, unit is specified instead
      ScriptTransfer(inv.caller, 5, unit) 
    ],
    unit
  )
}

Example 2
The assetInfo function requests information about the token by its ID. Next, the isDefined function checks that a token with this ID exists on the blockchain. 


let asset = assetInfo(base58'8LQW8f7P5d5PZM7GtZEBgaqRPGSzS3DfPuiXrURJ4AJS')
asset.isDefined()

Instead of calling the isDefined function, you may use the equality with unit. 


asset != unit
# Expression asset != unit is equivalent to the expression token.isDefined()

UpdateAssetInfoTransaction
Built-in Functions