RangeExtensions

This package enables the usage of System.Range in foreach expressions and provides extensions to integrate it with LINQ as a faster replacement to Enumerable.Range.

• Correctness is verified against IEnumerable<int> and Enumerable.Range behavior;
• Implementation tries its best to make abstractions either zero-cost or reasonably close to that. For critical paths, performance is tuned to be allocation-free and on par with regular for loops

Features

Range enumeration

foreach (var i in ..100) // you can write 0..Length as just ..Length
{
    Console.WriteLine(i);
}

Reverse range enumeration

for (var i = 100 - 1; i >= 0; i--)
{
    Console.WriteLine(i);
}

// Can be written as
foreach (var i in 100..0)
{
    Console.WriteLine(i);
}

Select and Where

var floats = (0..100).Select(i => (float)i);
var odd = (0..100).Where(i => i % 2 != 0);

var randomNumbers = (0..1000)
    .Select(_ => Random.Shared.Next())
    .ToArray();

Collecting to array or list

var numbers = (0..100).ToArray();

Aggregate

var digits = (0..10)
    .Aggregate(new StringBuilder(), (sb, i) => sb.Append(i))
    .ToString();

Assert.Equal("0123456789", digits);

Other LINQ specializations

var enumerable = (..100).AsEnumerable();

var sum = enumerable.Sum();
var count = enumerable.Count;
var average = enumerable.Average();
var firstTen = enumerable.Take(10);
var reversed = enumerable.Reverse();
// and others

Performance

In .NET 7, foreach (var i in 0..Length) has the same performance as for loop. Otherwise, RangeExtensions is 2 to >10 times faster than Enumerable.Range. Using DynamicPGO significantly improves the performance of both.

BenchmarkDotNet=v0.13.2, OS=macOS 13.1 (22C65) [Darwin 22.2.0]
Apple M1 Pro, 1 CPU, 8 logical and 8 physical cores
.NET SDK=8.0.100-alpha.1.22620.11
  [Host]     : .NET 7.0.1 (7.0.122.56804), Arm64 RyuJIT AdvSIMD
  DefaultJob : .NET 7.0.1 (7.0.122.56804), Arm64 RyuJIT AdvSIMD

Job=ShortRun  IterationCount=3  LaunchCount=1  
WarmupCount=3

DOTNET_TieredPGO=1
DOTNET_ReadyToRun=0

Method	Length	Mean	Error	Ratio	Allocated
For	1	0.0000 ns	0.0000 ns	?	-
Range	1	0.6531 ns	0.0051 ns	?	-
EnumerableRange	1	8.1135 ns	0.0198 ns	?	40 B
RangeSelect	1	1.1588 ns	0.0048 ns	?	-
EnumerableSelect	1	40.7948 ns	0.7697 ns	?	88 B
RangeSelectTwice	1	19.4165 ns	0.0480 ns	?	96 B
EnumerableSelectTwice	1	43.6399 ns	0.0908 ns	?	232 B
RangeWhere	1	1.3954 ns	0.0036 ns	?	-
EnumerableWhere	1	26.1945 ns	0.0534 ns	?	96 B
For	100	36.1897 ns	0.0618 ns	1.00	-
Range	100	36.9244 ns	2.0789 ns	1.00	-
EnumerableRange	100	211.4774 ns	0.6430 ns	5.85	40 B
RangeSelect	100	42.6852 ns	0.1689 ns	1.18	-
EnumerableSelect	100	235.7174 ns	0.5161 ns	6.51	88 B
RangeSelectTwice	100	110.1340 ns	0.1667 ns	3.04	96 B
EnumerableSelectTwice	100	298.2976 ns	2.7831 ns	8.22	232 B
RangeWhere	100	56.1455 ns	0.1701 ns	1.55	-
EnumerableWhere	100	249.1264 ns	1.5890 ns	6.89	96 B
For	100000	31,167.5682 ns	37.3266 ns	1.00	-
Range	100000	31,173.8688 ns	13.0666 ns	1.00	-
EnumerableRange	100000	212,925.2827 ns	156.8182 ns	6.83	40 B
RangeSelect	100000	50,086.3342 ns	39.0657 ns	1.61	-
EnumerableSelect	100000	204,113.5813 ns	100.0221 ns	6.55	88 B
RangeSelectTwice	100000	94,302.1444 ns	230.6254 ns	3.02	96 B
EnumerableSelectTwice	100000	203,946.9247 ns	908.5243 ns	6.56	232 B
RangeWhere	100000	47,165.0569 ns	36.7208 ns	1.51	-
EnumerableWhere	100000	209,918.1519 ns	3,298.4418 ns	6.76	96 B

More details on performance: Releases tab contains notes on improvements introduced with each version.