core.opt

Optional values: a payload or an explicit absence.

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Opt

enum Opt[T]

A value that may be absent. Match Val(value) or Non() to handle both cases.

let missing = Opt[Int].Non
print(missing.unwrap_or(7))

7

Source, line 12

Opt.Val

Val(T)

A present value of type T.

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Opt.Non

Non

No value.

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Opt[@T]

impl Opt[@T]

Source, line 19

Opt[@T].unwrap

func unwrap(self): T

Return the payload. Stop with an error if this is Non.

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Opt[@T].unwrap_or

func unwrap_or(self, default: T): T

Return the payload, or default when absent. Arguments are evaluated before the call.

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