RangeExtensions

This package allows you to use 0..100 in foreach expressions and implements RangeEnumerable that supports a variety of LINQ-like operations as well as ICollection<int> and IEnumerable<int>.

• Correctness is verified against standard IEnumerable<int> and Enumerable.Range behavior;
• Performance is hand tuned to produce efficient native code with no allocations as long as RangeEnumerable isn't boxed (same applies to enumerator). However, even when boxed it is still faster than Enumerable.Range.

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);
}

Collecting to array or list

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

IEnumerable<int> (some methods have bespoke implementations for performance)

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 short: 10x fast vs Enumerable.Range() and as fast as a plain for loop (there's small fixed overhead to check range correctness).

BenchmarkDotNet=v0.13.1, OS=Windows 10.0.22000
AMD Ryzen 7 5800X, 1 CPU, 16 logical and 8 physical cores
.NET SDK=7.0.100-rc.1.22363.32
  [Host]   : .NET 7.0.0 (7.0.22.36203), X64 RyuJIT
  ShortRun : .NET 7.0.0 (7.0.22.36203), X64 RyuJIT

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