Standard Library Prelude

The prelude is a list of commonly used features from the standard library which is automatically imported into every Sway program.

The prelude contains the following:

• Address: A struct containing a b256 value which represents the wallet address
• ContractId A struct containing a b256 value which represents the ID of a contract
• Identity: An enum containing Address & ContractID structs
• Vec: A growable, heap-allocated vector
• StorageMap: A key-value mapping in contract storage
• Option: An enum containing either some generic value <T> or an absence of that value, we also expose the variants directly:
  • Some
  • None
• Result: An enum used to represent either a success or failure of an operation, we also expose the variants directly:
  • Ok
  • Err
• assert: A module containing
  • assert: A function that reverts the VM if the condition provided to it is false
  • assert_eq: A function that reverts the VM and logs its two inputs v1 and v2 if the condition v1 == v2 is false
  • assert_ne: A function that reverts the VM and logs its two inputs v1 and v2 if the condition v1 != v2 is false
• revert: A module containing
  • require: A function that reverts and logs a given value if the condition is false
  • revert: A function that reverts
• log: A function that logs arbitrary stack types
• msg_sender: A function that gets the Identity from which a call was made