Nullable<'T>.Value → Nullable<'T>.GetValueOrDefault

[brianrourkeboll]

Description

• We are already checking Nullable<'T>.HasValue before accessing Nullable<'T>.Value, so it is safe to call Nullable<'T>.GetValueOrDefault. Nullable<'T>.Value does a redundant check of HasValue, while Nullable<'T>.GetValueOrDefault does not. Using GetValueOrDefault is significantly faster when no value is present.

Note: these functions are marked inline — does this change have any binary compatibility implications?

Benchmarks

Method	Mean	Error	StdDev	Ratio	RatioSD
Value_NoValue	0.2210 ns	0.0140 ns	0.0117 ns	1.00	0.07
GetValueOrDefault_NoValue	0.0368 ns	0.0106 ns	0.0089 ns	0.17	0.04
Value_Value	3.1128 ns	0.0731 ns	0.0610 ns	1.00	0.03
GetValueOrDefault_Value	3.0675 ns	0.0107 ns	0.0084 ns	0.99	0.02

Source

module OfNullable.Program

open System
open BenchmarkDotNet.Attributes
open BenchmarkDotNet.Configs
open BenchmarkDotNet.Running

[<GroupBenchmarksBy(BenchmarkLogicalGroupRule.ByCategory)>]
type Benchmarks () =
    let noValue = Nullable<int> ()
    let value = Nullable 3

    [<Benchmark(Baseline = true)>]
    [<BenchmarkCategory("NoValue")>]
    member _.Value_NoValue () = ValueOption.ofNullable noValue

    [<Benchmark>]
    [<BenchmarkCategory("NoValue")>]
    member _.GetValueOrDefault_NoValue () = if noValue.HasValue then ValueSome (noValue.GetValueOrDefault ()) else ValueNone

    [<Benchmark(Baseline = true)>]
    [<BenchmarkCategory("Value")>]
    member _.Value_Value () = ValueOption.ofNullable value

    [<Benchmark>]
    [<BenchmarkCategory("Value")>]
    member _.GetValueOrDefault_Value () = if value.HasValue then ValueSome (value.GetValueOrDefault ()) else ValueNone

ignore (BenchmarkRunner.Run<Benchmarks> ())

Checklist

• Test cases added.
• Performance benchmarks added in case of performance changes.
• Release notes entry updated.

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cc @dotnet/fsharp-team-msft

[vzarytovskii]

That's nice, thanks. I didn't even know about this API existence.

[psfinaki]

Thanks!

[psfinaki]

/azp run

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[psfinaki]

/azp run

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