std::option - Nullable values¶
func is_some¶
func is_some(enum {none, some: T}): bool
where T
Returns true iff the value is .some.
func is_none¶
func is_none(enum {none, some: T}): bool
where T
Returns true iff the value is .none.
The inverse of is_some.
func or_else¶
func or_else(enum {none, some: T}, fallback: T): T
where T
When value is .none, returns a fallback value instead.
func or_default¶
func or_default(enum {none, some: T}): T
where T
When value is .none, returns the default value instead.
Default value depends on the type. See super::default.
For numbers it is 0, for booleans it is false.
func zip¶
func zip(enum {none, some: A}, enum {none, some: B}): enum {none, some: {A, B}}
where A, B
Zips two options together into an option of a tuple.
Returns .some({a, b}) only if both a and b are .some.
func map¶
func map(enum {none, some: I}, func (I): O): enum {none, some: O}
where I, O
Maps value in .some. Does nothing if the value is .none.
func flat_map¶
func flat_map(enum {none, some: I}, func (I): enum {none, some: O}): enum {none, some: O}
where I, O
Maps value in .some. Does nothing if the value is .none.
func map_or¶
func map_or(enum {none, some: I}, fallback: O, func (I): O): O
where I, O
When value is .none returns fallback, otherwise maps value in .some.