Keywords

The following list contains keywords that are reserved for current or future use by the Sway language. As such, they cannot be used as identifiers. Identifiers are names of functions, variables, parameters, modules, constants, attributes, types or traits, etc.

Keywords Currently in Use

The following is an alphabetically sorted list of keywords currently in use, with their functionality shortly described.

  • as - rename items in use statements, e.g., use type::type_name as alias_name;
  • abi - define a smart contract ABI in a syntactically similar way to traits
  • asm - define an assembly block
  • break - exit a loop immediately
  • configurable - define configurable constants
  • const - define constant
  • continue - continue to the next loop iteration
  • contract - define contract program type
  • else - used in conjunction with if conditions for control flow constructs
  • enum - define an enum
  • false - Boolean false literal
  • for - loop based on iterators
  • fn- define a function
  • if - branch based on the result of a conditional expression
  • impl - implement inherent or trait functionality
  • let - bind a variable
  • library - define library program type
  • match - exhaustively match a value to patterns
  • mod - define a module
  • mut - denote mutability
  • pub - denote public visibility
  • predicate - define predicate program type
  • ref - bind by reference
  • return - return early from a function
  • script - define script program type
  • Self - a type alias for the type we are defining or implementing
  • self - method call target
  • storage - define a storage declaration
  • str- string slice
  • struct - define a structure
  • trait - define a trait
  • true - Boolean true literal
  • type - define a type alias or associated type
  • use - bring symbols into scope
  • where - specifies trait constraints for generic type arguments
  • while - loop conditionally based on the result of an expression

Keywords Reserved for Possible Future Use

  • abstract
  • async
  • await
  • become
  • box
  • do
  • dyn
  • extern
  • for
  • in
  • loop
  • macro
  • move
  • override
  • priv
  • static
  • super
  • try
  • typeof
  • unsafe
  • unsized
  • virtual
  • yield