Lambda vs method group

This article will show the differences between a lamdbda expression and a method group.

Prefer lambda expression over method groups

Lambda expression can be cached by the .net runtime where as methods groups are not. This can lead to additional allocations if you use .net6 or below (it was improved with .net7).

❌ Bad Use method group.

_ints.Where(IsEven);

✅ Good Use lambda expression.

_ints.Where(i => IsEven(i));

Benchmark

public class LambdaVsMethodGroup
{
    private IEnumerable<int> _ints = Enumerable.Range(0, 100);

    [Benchmark(Baseline = true)]
    public List<int> MethodGroup() => _ints.Where(IsEven).ToList();

    [Benchmark]
    public List<int> Lambda() => _ints.Where(i => IsEven(i)).ToList();

    private static bool IsEven(int i) => i % 2 == 0;
}

Results:

|      Method |     Mean |    Error |   StdDev | Ratio | RatioSD |
|------------ |---------:|---------:|---------:|------:|--------:|
| MethodGroup | 570.4 ns | 10.88 ns | 11.18 ns |  1.00 |    0.00 |
|      Lambda | 517.6 ns |  6.20 ns |  5.80 ns |  0.91 |    0.02 |