A set of extensions functions written on object, by default available in Kotlin, ported for c#.

KotlinObjectExtensions.cs

using System;
using System.Runtime.CompilerServices;
using System.Threading.Tasks;

namespace Utilities
{
    public static class KotlinObjectExtensions
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T Also<T>(this T callee, Action<T> action)
        {
            action(callee);
            return callee;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<T> Also<T>(this T callee, Func<T, Task> action)
        {
            await action(callee);
            return callee;
        }

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static TResult Let<T, TResult>(this T callee, Func<T, TResult> func) =>
            func(callee);

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<TResult> Let<T, TResult>(this T callee, Func<T, Task<TResult>> func) =>
            await func(callee);

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static void Let<T>(this T callee, Action<T> func) =>
            func(callee);

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task Let<T>(this T callee, Func<T, Task> func) =>
            await func(callee);

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T? TakeIf<T>(this T callee, Func<T, bool> predicate) =>
            predicate(callee) ? callee : default;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static async Task<T?> TakeIf<T>(this T callee, Func<T, Task<bool>> predicate) =>
            await predicate(callee) ? callee : default;

        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        public static T? TakeIf<T>(this T callee, bool condition) =>
            condition ? callee : default;
    }
}