Change Sampler methods to return Sequence instead of List #4807
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Sequence is a covariant type (Sequence[A] is a subclass of Sequence[B] when A is a subclass of B) while List is invariant (List[A] is not a subclass of List[B] even in A is a subclass of B). Returning Sequence[cirq.Result] thus allows returning subtypes of cirq.Result, while List[cirq.Result] does not.
maffoo
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cduck,
ColemanCollins,
dabacon,
gmauricio,
ma5x,
mrwojtek,
nakardo,
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vtomole,
wcourtney and
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viathor
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Jan 6, 2022
MichaelBroughton
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Jan 22, 2022
…#4807) Sequence is a covariant type (Sequence[A] is a subclass of Sequence[B] when A is a subclass of B) while List is invariant (List[A] is not a subclass of List[B] even in A is a subclass of B). Returning Sequence[cirq.Result] thus allows returning subtypes of cirq.Result, while List[cirq.Result] does not. Review: @viathor
rht
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May 1, 2023
…#4807) Sequence is a covariant type (Sequence[A] is a subclass of Sequence[B] when A is a subclass of B) while List is invariant (List[A] is not a subclass of List[B] even in A is a subclass of B). Returning Sequence[cirq.Result] thus allows returning subtypes of cirq.Result, while List[cirq.Result] does not. Review: @viathor
harry-phasecraft
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this pull request
Oct 31, 2024
…#4807) Sequence is a covariant type (Sequence[A] is a subclass of Sequence[B] when A is a subclass of B) while List is invariant (List[A] is not a subclass of List[B] even in A is a subclass of B). Returning Sequence[cirq.Result] thus allows returning subtypes of cirq.Result, while List[cirq.Result] does not. Review: @viathor
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Sequenceis a covariant type (Sequence[A]is a subclass ofSequence[B]whenAis a subclass ofB) whileList, because it is mutable, is invariant (List[A]is not a subclass ofList[B]even ifAis a subclass ofB). ReturningSequence[cirq.Result]thus allows returning subtypes ofcirq.Result, whileList[cirq.Result]does not.We change
cirq.Samplermethodsrun_sweepandrun_batchto returnSequence[cirq.Result]andSequence[Sequence[cirq.Result]], respectively, which makes it possible to return result subtypes if desired, as needed in #4806.