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Rystem 10.0.8

What is Rystem?

Rystem

Rystem is the core utilities package of the Rystem ecosystem.

It extends familiar BCL namespaces such as System, System.Linq, System.Linq.Expressions, System.Reflection, System.Text, and System.Threading.Tasks with pragmatic helpers for:

• discriminated unions in C#
• expression serialization and dynamic LINQ/queryable composition
• reflection, mocking, runtime model generation, and IL inspection
• JSON, CSV, minimization, hashing, and encoding helpers
• task orchestration and small concurrent collections

Most examples below are adapted from the repository test suite so the README stays aligned with real usage. For brevity, short snippets sometimes use obvious sample types such as User, Order, MyType, or MyDto.

Resources

• Complete Documentation: https://rystem.net
• MCP Server for AI: https://rystem.cloud/mcp
• Discord Community: https://discord.gg/tkWvy4WPjt
• Support the Project: https://www.buymeacoffee.com/keyserdsoze

Installation

dotnet add package Rystem

The current 10.x package targets net10.0.

After installation, most APIs are available through standard using directives that match the namespace they extend. The main exception is ReflectionHelper, which lives in Rystem.Reflection.

If you move deeper into the ecosystem, Rystem.DependencyInjection builds DI modules on top of this package, and Rystem.DependencyInjection.Web adds ASP.NET Core runtime rebuilding on top of the DI layer.

Table of Contents

• Package Architecture
• Discriminated Unions in C#
  • Define a union
  • Match, Switch, and TryGet
  • JSON serialization and deserialization
  • Resolving ambiguous JSON with selectors
  • Class-level selectors, regex selectors, and default types
• Core Utilities
• Stopwatch
• Try / Retry
• Cast extensions
• Copy extensions
• Enum extensions
• Text extensions
• Encoding: Base64 and Base45
  • Base64
  • Base45
• Cryptography (Hashing)
• JSON extensions
• CSV and Minimization
• CSV
• Minimization
• LINQ and Expression Utilities
• Serialize and deserialize lambda expressions
• Dynamic lambda utilities
• Dynamic IQueryable helpers
• RemoveWhere
• AllAsync and AnyAsync
• Non-generic IEnumerable helpers
• Reflection and Runtime Tools
• Name of the calling class
• Cached reflection helpers
• Type relationship helpers
• Create default instances
• Mock abstract classes and interfaces
• Construct with the best dynamic fit
• Nullability inspection
• Property showcase
• IL inspection and method signatures
• Runtime model builder
• Generic method invocation
• Tasks and Collections
• NoContext and ToResult
• ToListAsync
• TaskManager
  • WhenAll
  • WhenAtLeast
• ConcurrentList
• Utilities
• AsyncEnumerable.Empty
• Programming language conversion
• Repository Examples

---

Package Architecture

Area	Main APIs
Discriminated unions	AnyOf<T0, ...>, Match, MatchAsync, Switch, SwitchAsync, TryGetTn, JSON selectors and defaults
Core helpers	Stopwatch, Try, Cast<T>, ToDeepCopy, CopyPropertiesFrom, enum and string helpers
Text and data	ToByteArray, ToStream, ReadLinesAsync, ToJson, ToHash, ToBase64, ToBase45, ToCsv, ToMinimize
LINQ and expressions	Serialize, Deserialize, DeserializeAsDynamic, ChangeReturnType, InvokeAsync, Where(LambdaExpression), Select(LambdaExpression), CallMethodAsync
Reflection and runtime	FetchProperties, CreateWithDefault, CreateInstance, ConstructWithBestDynamicFit, ToShowcase, GetBodyAsString, Model.Create(...)
Tasks and collections	NoContext, ToResult, ToListAsync, TaskManager, ConcurrentList<T>, AsyncEnumerable<T>.Empty
Conversion	ConvertAs(ProgrammingLanguageType.Typescript)

If you want a single package with a broad set of low-level .NET utilities, this is the entry point of the Rystem ecosystem.

---

Discriminated Unions in C#

AnyOf<T0, T1, ...> brings discriminated unions to C# with built-in System.Text.Json integration.

The package ships AnyOf variants from 2 to 10 generic arguments.

Define a union

AnyOf<int, string, bool> value = "hello";

Console.WriteLine(value.Index); // 1
Console.WriteLine(value.IsT1); // true
Console.WriteLine(value.AsT1); // hello

value = 42;
int number = value.CastT0;

Useful members include:

• Index
• IsT0, IsT1, ...
• AsT0, AsT1, ...
• CastT0, CastT1, ...
• Is<T>()
• TryGetT0(out value), TryGetT1(out value), ...

Match, Switch, and TryGet

AnyOf<int, string, bool> value = "hello";

string description = value.Match(
 number => $"int: {number}",
 text => $"string: {text}",
 flag => $"bool: {flag}")!;

value.Switch(
 number => Console.WriteLine(number),
 text => Console.WriteLine(text),
 flag => Console.WriteLine(flag));

string? asyncDescription = await value.MatchAsync(
 async number => await Task.FromResult($"int: {number}"),
 async text => await Task.FromResult($"string: {text}"),
 async flag => await Task.FromResult($"bool: {flag}"));

await value.SwitchAsync(
 number => { Console.WriteLine(number); return ValueTask.CompletedTask; },
 text => { Console.WriteLine(text); return ValueTask.CompletedTask; },
 flag => { Console.WriteLine(flag); return ValueTask.CompletedTask; });

if (value.TryGetT1(out var textValue))
 Console.WriteLine(textValue);

Notes:

• MatchAsync delegates return Task<TResult?>
• SwitchAsync delegates return ValueTask
• TryGetTn is the safest way to branch without exceptions

JSON serialization and deserialization

The active value is serialized directly, and deserialization automatically chooses the correct target type.

public sealed class Wrapper
{
 public AnyOf<FirstClass, string>? Data { get; set; }
}

public sealed class FirstClass
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

var wrapper = new Wrapper
{
 Data = new FirstClass
 {
 FirstProperty = "alpha",
 SecondProperty = "beta"
 }
};

string json = wrapper.ToJson();
Wrapper copy = json.FromJson<Wrapper>();

Console.WriteLine(copy.Data!.AsT0!.FirstProperty); // alpha

By default, union deserialization uses the JSON payload signature, meaning the set of available property names is used to find the best candidate.

public sealed class SignatureTestClass
{
 public AnyOf<SignatureClassOne, SignatureClassTwo>? Test { get; set; }
}

public sealed class SignatureClassOne
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

public sealed class SignatureClassTwo
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

var payload = new SignatureTestClass
{
 Test = new SignatureClassTwo
 {
 FirstProperty = "FirstProperty",
 SecondProperty = "SecondProperty"
 }
};

var copy = payload.ToJson().FromJson<SignatureTestClass>();

// Both candidate types have the same signature,
// so the first matching type wins.
Console.WriteLine(copy.Test!.Is<SignatureClassOne>()); // true

If no candidate can be matched, the union property is deserialized as null.

Resolving ambiguous JSON with selectors

When multiple candidate types share the same shape, add selectors to tell the deserializer how to choose.

AnyOfJsonSelector works with both strings and non-string values.

public sealed class ChosenClass
{
 public AnyOf<TheFirstChoice, TheSecondChoice>? Value { get; set; }
}

public sealed class TheFirstChoice
{
 [AnyOfJsonSelector("first")]
 public string Type { get; init; } = null!;

 [AnyOfJsonSelector(2, 3, 4)]
 public int Flexy { get; set; }
}

public sealed class TheSecondChoice
{
 [AnyOfJsonSelector("first", "second")]
 public string Type { get; init; } = null!;

 [AnyOfJsonSelector(1)]
 public int Flexy { get; set; }
}

var payload = new ChosenClass
{
 Value = new TheSecondChoice
 {
 Type = "first",
 Flexy = 1
 }
};

var copy = payload.ToJson().FromJson<ChosenClass>();
Console.WriteLine(copy.Value!.Is<TheSecondChoice>()); // true

payload = new ChosenClass
{
 Value = new TheSecondChoice
 {
 Type = "first",
 Flexy = 2
 }
};

copy = payload.ToJson().FromJson<ChosenClass>();
Console.WriteLine(copy.Value!.Is<TheFirstChoice>()); // true

In the second case, the raw object was originally TheSecondChoice, but the selector values identify TheFirstChoice as the correct deserialization target.

Class-level selectors, regex selectors, and default types

You can apply selectors to a whole class instead of a single property.

[AnyOfJsonClassSelector(nameof(FirstProperty), "first.F")]
public sealed class FirstGetClass
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

[AnyOfJsonRegexClassSelector(nameof(FirstProperty), "secon[^.]*.[^.]*")]
public sealed class SecondGetClass
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

public sealed class FourthGetClass
{
 [AnyOfJsonSelector("fourth.F")]
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

public sealed class FifthGetClass
{
 [AnyOfJsonRegexSelector("fift[^.]*.")]
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

[AnyOfJsonDefault]
public sealed class SixthGetClass
{
 public string? FirstProperty { get; set; }
 public string? SecondProperty { get; set; }
}

This lets you combine:

• exact value selectors
• regex selectors
• class-level selectors
• a default fallback type when no other selector matches

---

Core Utilities

Stopwatch

Measure actions, tasks, or task-returning functions.

var started = Stopwatch.Start();
await Task.Delay(2000);
var result = started.Stop();

Console.WriteLine(result.Span.TotalMilliseconds);

var result = await Stopwatch.MonitorAsync(async () =>
{
 await Task.Delay(2000);
});

Console.WriteLine(result.Span.TotalMilliseconds);

var result = await Stopwatch.MonitorAsync(async () =>
{
 await Task.Delay(2000);
 return 3;
});

Console.WriteLine(result.Result); // 3
Console.WriteLine(result.Stopwatch.Span); // elapsed time

There is also a synchronous overload:

var result = Stopwatch.Monitor(() => DoWork());

Try / Retry

Try wraps synchronous, Task, and ValueTask execution and returns the value plus any exception.

var success = Try.WithDefaultOnCatch(() => 42);
int value = success;

Console.WriteLine(value); // 42
Console.WriteLine(success.Exception == null); // true

var failed = Try.WithDefaultOnCatch(() => int.Parse("abc"));

Console.WriteLine((int)failed); // 0
Console.WriteLine(failed.Exception != null); // true

var asyncFailed = await Try.WithDefaultOnCatchAsync(async () =>
{
 await Task.Delay(10);
 return int.Parse("abc");
});

Console.WriteLine(asyncFailed.Exception != null); // true

var valueTaskResult = await Try.WithDefaultOnCatchValueTaskAsync(async () =>
{
 await Task.Delay(10);
 return 12;
});

You can also configure retry behavior.

var response = await Try.WithDefaultOnCatchAsync(
 async () => await FlakyServiceAsync(),
 behavior =>
 {
 behavior.MaxRetry = 3;
 behavior.WaitBetweenRetry = 200;
 behavior.RetryUntil = exception => exception is HttpRequestException;
 });

Prefer checking response.Exception to detect failures. That is the most explicit and reliable success signal.

Cast extensions

Use Cast<T>() for safe conversions across numeric values, strings, runtime types, and inheritance hierarchies.

int x = 2;
decimal result = x.Cast<decimal>();

int? nullable = null;
decimal result2 = nullable.Cast<decimal>(); // 0
decimal? result3 = nullable.Cast<decimal?>(); // null

string guid = Guid.NewGuid().ToString();
Guid parsed = guid.Cast<Guid>();

object entity = new User();
Type targetType = typeof(UserDto);
object converted = entity.Cast(targetType)!;

Copy extensions

Use ToDeepCopy() to create a detached clone, or CopyPropertiesFrom(...) to copy property values onto an existing instance.

var original = new User { Id = 3 };
var copy = original.ToDeepCopy();

Console.WriteLine(ReferenceEquals(original, copy)); // false
Console.WriteLine(copy.Id); // 3

var source = new User { Id = 10 };
var target = new User();

target.CopyPropertiesFrom(source);
Console.WriteLine(target.Id); // 10

Enum extensions

Convert strings or other enum values into a target enum and read [Display] names.

enum Color
{
 Red,
 Green,
 Blue
}

Color c1 = "green".ToEnum<Color>();
Color c2 = ConsoleColor.Green.ToEnum<Color>();

public enum Status
{
 [Display(Name = "In Progress")]
 Working
}

string label = Status.Working.GetDisplayName(); // In Progress

Text extensions

Convert between strings, byte arrays, and streams with minimal ceremony.

string text = "daskemnlandxioasndslam dasmdpoasmdnasndaslkdmlasmv asmdsa";

byte[] bytes = text.ToByteArray();
string restored = bytes.ConvertToString();

string text = "daskemnlandxioasndslam dasmdpoasmdnasndaslkdmlasmv asmdsa";

Stream stream = text.ToStream();
string restored = stream.ConvertToString();

ReadLinesAsync() turns a stream into IAsyncEnumerable<string>.

string text = "line 1\nline 2\nline 3";
Stream stream = text.ToStream();

await foreach (var line in stream.ReadLinesAsync())
{
 Console.WriteLine(line);
}

Other small helpers:

string title = "dasda".ToUpperCaseFirst(); // Dasda
bool hasTwoAs = "abcderfa".ContainsAtLeast(2, 'a');
string replaced = "aaa".Replace("a", "b", 2); // bba

Encoding: Base64 and Base45

Base64

string encoded = "Hello World".ToBase64();
string decoded = encoded.FromBase64();

var payload = new User { Id = 7, Name = "Ada" };
string encodedObject = payload.ToBase64();
User decodedObject = encodedObject.FromBase64<User>();

Base45

Base45 is handy when you want a compact, QR-code-friendly character set.

string encoded = "Hello World".ToBase45();
string decoded = encoded.FromBase45();

var payload = new User { Id = 7, Name = "Ada" };
string encodedObject = payload.ToBase45();
User decodedObject = encodedObject.FromBase45<User>();

Both object overloads serialize through JSON first.

Cryptography (Hashing)

ToHash() creates a deterministic SHA-512 hexadecimal hash from a string or any serializable object.

string hash = "my secret".ToHash();

var foo = new Foo
{
 Values = new[] { "aa", "bb", "cc" },
 X = true
};

string hash2 = foo.ToHash();
Console.WriteLine(foo.ToHash() == hash2); // true

Guid id = Guid.Parse("41e2c840-8ba1-4c0b-8a9b-781747a5de0c");
string hash = id.ToHash();

JSON extensions

The JSON helpers are intentionally tiny wrappers over System.Text.Json.

var users = new List<User>
{
 new User { Id = 1, Name = "Ada" },
 new User { Id = 2, Name = "Grace" }
};

string json = users.ToJson();
List<User> copy = json.FromJson<List<User>>();

object? dynamicCopy = json.FromJson(typeof(List<User>));

await using var stream = json.ToStream();
List<User> fromStream = await stream.FromJsonAsync<List<User>>();

---

CSV and Minimization

CSV

ToCsv() flattens objects, nested objects, and enumerable members into a tabular representation.

string csv = models.ToCsv();

You can configure headers, delimiters, Excel-friendly quoting, and excluded properties.

string csv = users.ToCsv(configuration =>
{
 configuration.ForExcel = true;
 configuration.UseExtendedName = false;
 configuration.ConfigureHeader(x => x.Id, "Identifier");
 configuration.ConfigureHeader(x => x.Groups.First().Name, "GroupName");
 configuration.AvoidProperty(x => x.Password);
 configuration.Delimiter = ";";
});

Configuration options include:

• UseHeader
• Delimiter
• ForExcel
• UseExtendedName
• ConfigureHeader(...)
• AvoidProperty(...)

Minimization

ToMinimize() is a compact serializer designed to occupy less space than JSON for many object graphs.

string minimized = models.ToMinimize();
List<CsvModel> restored = minimized.FromMinimization<List<CsvModel>>();

You can also choose the starting separator explicitly.

string minimized = models.ToMinimize('&');
List<CsvModel> restored = minimized.FromMinimization<List<CsvModel>>('&');

Use MinimizationPropertyAttribute when you want deterministic property ordering.

public sealed class CompactUser
{
 [MinimizationProperty(0)]
 public int Id { get; set; }

 [MinimizationProperty(1)]
 public string? Name { get; set; }
}

---

LINQ and Expression Utilities

Serialize and deserialize lambda expressions

Rystem can serialize expression trees to strings and build them back into executable expressions.

var q = "dasda";
var id = Guid.Parse("bf46510b-b7e6-4ba2-88da-cef208aa81f2");

Expression<Func<MakeIt, bool>> expression =
 x => x.X == q &&
 x.Samules!.Any(y => y == "ccccde") &&
 x.Sol &&
 (x.X.Contains(q) || x.Sol.Equals(true)) &&
 (x.E == id | x.Id == 32);

string serialized = expression.Serialize();
Func<MakeIt, bool> compiled = serialized.DeserializeAndCompile<MakeIt, bool>();

List<MakeIt> filtered = makes.Where(compiled).ToList();

The test suite covers scenarios such as:

• Contains(...)
• Any(...)
• enum comparisons
• DateTime comparisons
• TimeSpan comparisons
• unary !
• nested member access

Dynamic lambda utilities

You can deserialize to LambdaExpression, inspect the inferred result type, convert the return type, and cast back to typed expressions.

Expression<Func<User, int>> selector = x => x.Id;
string text = selector.Serialize();

LambdaExpression dynamicSelector = text.DeserializeAsDynamic<User>();
Expression<Func<User, int>> asInt = dynamicSelector.AsExpression<User, int>();
Expression<Func<User, decimal>> asDecimal = dynamicSelector.AsExpression<User, decimal>();

decimal average = new List<User> { new User { Id = 13 } }.Average(asDecimal.Compile());

var inferred = "x => x.Id == 25".DeserializeAsDynamicAndRetrieveType<User>();

Console.WriteLine(inferred.Type); // System.Boolean

Expression<Func<User, ValueTask<int>>> expression = x => GetUserIdAsync(x);
LambdaExpression lambda = expression;

decimal id = await lambda.InvokeAsync<decimal>(new User { Id = 13 });

InvokeAndTransform(...) is also available when you want a converted return type from a compiled expression.

Expression<Func<User, int>> expression = x => x.Id;
decimal result = expression.InvokeAndTransform<User, int, decimal>(new User { Id = 13 })!;

You can also extract a property directly from an expression.

PropertyInfo? property = ((Expression<Func<User, int>>)(x => x.Id)).GetPropertyFromExpression();

Dynamic IQueryable helpers

The package exposes dynamic IQueryable operators that accept LambdaExpression instead of strongly typed selectors.

Supported helpers include:

• Average
• Count
• DistinctBy
• GroupBy
• LongCount
• Max
• Min
• OrderBy
• OrderByDescending
• Select
• Sum
• ThenBy
• ThenByDescending
• Where

Expression<Func<MakeIt, int>> orderExpression = x => x.Id;
Expression<Func<MakeIt, bool>> predicateExpression = x => x.Id >= 10;

LambdaExpression orderBy = orderExpression.Serialize().DeserializeAsDynamic<MakeIt>();
LambdaExpression predicate = predicateExpression.Serialize().DeserializeAsDynamic<MakeIt>();

var query = makes.AsQueryable();

var ordered = query.OrderByDescending(orderBy).ThenBy(orderBy).ToList();
var filtered = query.Where(predicate).ToList();
var grouped = query.GroupBy(orderBy).ToList();
var projected = query.Select<MakeIt, decimal>(orderBy).ToList();

var average = query.Average(orderBy);
var sum = query.Sum(orderBy);
var count = query.Count(predicate);

CallMethodAsync(...) lets you invoke custom async query operators dynamically.

public static class QueryableExtensions
{
 public static async Task<IQueryable<T>> GetAsync<T>(
 this IQueryable<T> queryable,
 Expression<Func<T, bool>> expression,
 CancellationToken cancellationToken = default)
 {
 await Task.Delay(0);
 return queryable.Where(expression);
 }
}

var result = await query.CallMethodAsync<MakeIt, IQueryable<MakeIt>>(
 "GetAsync",
 predicate,
 typeof(QueryableExtensions));

This is especially useful when you need to bridge runtime-generated selectors with LINQ providers such as Entity Framework.

RemoveWhere

RemoveWhere(...) works on arrays, ICollection<T>, and plain IEnumerable<T>.

int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
numbers = numbers.RemoveWhere(x => x == 8 || x == 9);

var filtered = myEnumerable.RemoveWhere(x => x.IsExpired);

List<Order> orders = GetOrders();
int removed = orders.RemoveWhere(x => x.Status == OrderStatus.Cancelled);

AllAsync and AnyAsync

Use async predicates over a synchronous IEnumerable<T>.

bool allValid = await items.AllAsync(x => ValueTask.FromResult(x.Id >= 0));
bool anyZero = await items.AnyAsync(x => Task.FromResult(x.Id == 0));

Both Task<bool> and ValueTask<bool> predicates are supported.

Non-generic IEnumerable helpers

The non-generic helpers are useful when you receive IEnumerable at runtime and still need indexed operations.

IEnumerable items = GetItems();

object? value = items.ElementAt(10);
items.SetElementAt(10, newValue);

bool removed = items.RemoveElementAt(10, out IEnumerable newItems, out object? removedValue);

They work with both Array and IList implementations.

---

Reflection and Runtime Tools

Name of the calling class

ReflectionHelper lives in Rystem.Reflection.

using Rystem.Reflection;

string name = ReflectionHelper.NameOfCallingClass(deep: 1);
string fullName = ReflectionHelper.NameOfCallingClass(deep: 1, full: true);

Increase deep when you want to walk further up the call stack.

Cached reflection helpers

The package caches repeated reflection lookups for better reuse.

PropertyInfo[] properties = typeof(MyType).FetchProperties();
ConstructorInfo[] constructors = typeof(MyType).FecthConstructors();
FieldInfo[] fields = typeof(MyType).FetchFields();
MethodInfo[] methods = typeof(MyType).FetchMethods();
MethodInfo[] staticMethods = typeof(MyType).FetchStaticMethods();

FetchProperties(...) can ignore properties decorated with specific attributes.

PropertyInfo[] visibleProperties = typeof(MyType).FetchProperties(typeof(JsonIgnoreAttribute));

Type relationship helpers

bool sameOrSon = typeof(Folli).IsTheSameTypeOrASon(typeof(Sulo));
bool sameOrParent = typeof(Sulo).IsTheSameTypeOrAParent(typeof(Folli));
bool hasInterface = typeof(MyService).HasInterface<IDisposable>();

Instance overloads are available too.

Zalo zalo = new();
Sulo sulo = new();

Console.WriteLine(zalo.IsTheSameTypeOrASon(sulo));
Console.WriteLine(sulo.IsTheSameTypeOrAParent(zalo));

Create default instances

CreateWithDefault() builds an instance by recursively creating default constructor arguments and common collection implementations.

public sealed class Foo
{
 public IEnumerable<string> Values { get; }
 public Foo(IEnumerable<string> values) => Values = values;
}

Foo foo = typeof(Foo).CreateWithDefault<Foo>()!;
(foo.Values as List<string>)!.Add("aaa");

CreateWithDefaultConstructorPropertiesAndField() goes further and populates settable properties and fields as well.

Foo2 foo = typeof(Foo2).CreateWithDefaultConstructorPropertiesAndField<Foo2>()!;

foo.Complex.Add("x", "y");
(foo.Tiny.Values as List<string>)!.Add("aaa");

Mock abstract classes and interfaces

Rystem can generate runtime implementations for abstract classes and interfaces.

public abstract class Alzio
{
 private protected string X { get; }
 public string O => X;
 public string A { get; set; }

 protected Alzio(string x) => X = x;
}

var mocked = typeof(Alzio).CreateInstance("AAA") as Alzio;
mocked!.A = "rrrr";

Console.WriteLine(mocked.O); // AAA
Console.WriteLine(mocked.A); // rrrr

You can also configure the generated type.

Alzio alzio = null!;

var configured = alzio.CreateInstance(configuration =>
{
 configuration.IsSealed = false;
 configuration.CreateNewOneIfExists = true;
}, "AAA");

Construct with the best dynamic fit

ConstructWithBestDynamicFit(...) matches runtime arguments first against constructor parameters and then against settable properties.

var entity = (MySuperClass)typeof(MySuperClass).ConstructWithBestDynamicFit(3, 4, 5, 6)!;
var entity2 = Constructor.InvokeWithBestDynamicFit<MySuperClass>(5, 6, 7, 8);
var interfaceInstance = Constructor.InvokeWithBestDynamicFit<IMogalo>(9, 10, 11, 21);

This is useful when the values are only known at runtime and you still want a best-effort, exact-type match.

Nullability inspection

IsNullable() works on properties, fields, and parameters.

var type = typeof(InModel);

var constructorParameters = type.GetConstructors().First().GetParameters();
var methodParameters = type.GetMethod(nameof(InModel.SetSomething))!.GetParameters();
var properties = type.GetProperties();
var fields = type.GetFields();

Console.WriteLine(constructorParameters[0].IsNullable());
Console.WriteLine(methodParameters[0].IsNullable());
Console.WriteLine(properties[0].IsNullable());
Console.WriteLine(fields[0].IsNullable());

Property showcase

ToShowcase() builds a structured description of a type and can attach extra computed metadata to each flattened property.

var showcase = typeof(Something).ToShowcase(
 IFurtherParameter.Create("Bootstrap", x => new BootstrapProperty(x)),
 IFurtherParameter.Create("Title", x => x.NavigationPath));

var first = showcase.FlatProperties.First();
string title = first.GetProperty<string>("Title");
BootstrapProperty bootstrap = first.GetProperty<BootstrapProperty>("Bootstrap");

This is handy for metadata-driven UI generation, forms, and schema exploration.

IL inspection and method signatures

Inspect the body of a method as text or as decoded IL instructions.

MethodInfo method = typeof(Sulo).GetMethod(nameof(Sulo.Something), BindingFlags.Public | BindingFlags.Instance)!;

string body = method.GetBodyAsString();
List<ILInstruction> instructions = method.GetInstructions();
string signature = method.ToSignature();

This is useful for diagnostics, analysis tools, or advanced runtime inspection.

Runtime model builder

Create types dynamically at runtime.

var modelName = "MyBestModel";

Type modelType = Model
 .Create(modelName)
 .AddProperty("Primary", typeof(int))
 .AddProperty("Secondary", typeof(bool))
 .AddProperty("Name", typeof(string))
 .AddProperty("Id", typeof(Guid))
 .AddProperty("InModel", typeof(InModel))
 .AddParent<SomethingNew>()
 .Build();

dynamic instance = Model.Construct(modelName);
instance.Primary = 45;
instance.B = "Aloa";

This gives you a runtime-generated type plus a strongly discoverable builder API.

Generic method invocation

Generics.With(...) and Generics.WithStatic(...) let you bind generic methods by runtime type and invoke them later.

var staticResult = await Generics
 .WithStatic<SystemReflection>(nameof(StaticCreateAsync), typeof(int))
 .InvokeAsync(3);

var host = new SystemReflection();

var instanceResult = await Generics
 .With<SystemReflection>(nameof(CreateAsync), typeof(int))
 .InvokeAsync(host, 3);

int value = Generics
 .WithStatic<SystemReflection>(nameof(StaticCreate), typeof(int))
 .Invoke<int>(3)!;

---

Tasks and Collections

NoContext and ToResult

NoContext() is a small convenience wrapper around ConfigureAwait(...), controlled by RystemTask.WaitYourStartingThread.

await DoSomethingAsync().NoContext();
int result = GetValueAsync().ToResult();

If you need to preserve the original synchronization context, set:

RystemTask.WaitYourStartingThread = true;

ToListAsync

The package adds a small IAsyncEnumerable<T> helper.

await using var stream = "line 1\nline 2\nline 3".ToStream();
List<string> lines = await stream.ReadLinesAsync().ToListAsync();

TaskManager

TaskManager helps you run a bounded number of tasks concurrently.

WhenAll

var bag = new ConcurrentBag<int>();

await TaskManager.WhenAll(ExecuteAsync, times: 45, concurrentTasks: 12, runEverytimeASlotIsFree: true).NoContext();

async Task ExecuteAsync(int i, CancellationToken cancellationToken)
{
 await Task.Delay(i * 20, cancellationToken).NoContext();
 bag.Add(i);
}

It also works with collections of objects.

await TaskManager.WhenAll(ProcessAsync, orders, concurrentTasks: 5).NoContext();

async Task ProcessAsync(Order order, CancellationToken cancellationToken)
{
 await SaveAsync(order, cancellationToken).NoContext();
}

WhenAtLeast

WhenAtLeast(...) stops waiting as soon as the requested number of tasks has completed.

var bag = new ConcurrentBag<int>();

await TaskManager.WhenAtLeast(ExecuteAsync, times: 45, atLeast: 16, concurrentTasks: 12).NoContext();

async Task ExecuteAsync(int i, CancellationToken cancellationToken)
{
 await Task.Delay(i * 20, cancellationToken).NoContext();
 bag.Add(i);
}

ConcurrentList

ConcurrentList<T> is a small thread-safe wrapper around List<T> for common list operations.

var items = new ConcurrentList<MyClass>();

items.Add(new MyClass());
items.Insert(0, new MyClass());
items.RemoveAt(0);

Console.WriteLine(items.Count);

Use it when you want a simple IList<T> implementation with locking around the common mutating APIs.

---

Utilities

AsyncEnumerable.Empty

AsyncEnumerable<T>.Empty gives you a typed empty IAsyncEnumerable<T>.

using System.Collection.Generics;

IAsyncEnumerable<MyClass> empty = AsyncEnumerable<MyClass>.Empty;

await foreach (var item in empty)
{
 // never reached
}

Programming language conversion

The package can convert CLR types into other language representations. Right now it supports TypeScript.

using System.ProgrammingLanguage;

ProgrammingLanguangeResponse ts = typeof(MyDto)
 .ConvertAs(ProgrammingLanguageType.Typescript);

Console.WriteLine(ts.Text);
Console.WriteLine(ts.MimeType);

ProgrammingLanguangeResponse ts = new[] { typeof(OrderDto), typeof(ProductDto) }
 .ConvertAs(ProgrammingLanguageType.Typescript);

ProgrammingLanguangeResponse renamed = typeof(MyInternalClass)
 .ConvertAs(ProgrammingLanguageType.Typescript, "PublicDto");

The generated output understands common primitives, arrays, enumerables, dictionaries, enums, and nested types. It also respects JsonPropertyNameAttribute when present.

---

Repository Examples

If you want to see more real-world examples, the best references are the repository tests:

• Discriminated unions: src/Core/Test/Rystem.Test.UnitTest/System/DiscriminatedUnionTests.cs
• LINQ and dynamic queryable helpers: src/Core/Test/Rystem.Test.UnitTest/System.Linq/SystemLinq.cs
• Expression serialization and dynamic lambdas: src/Core/Test/Rystem.Test.UnitTest/System.Linq.Expression/SystemLinqExpressions.cs
• Reflection helpers: src/Core/Test/Rystem.Test.UnitTest/System.Reflection/ReflectionTest.cs
• Generic reflection and constructor fitting: src/Core/Test/Rystem.Test.UnitTest/System.Reflection/SystemReflection.cs
• Property showcase: src/Core/Test/Rystem.Test.UnitTest/System.Reflection/PropertyHandlerTest.cs
• Runtime model builder: src/Core/Test/Rystem.Test.UnitTest/System.Reflection/ModelTest.cs
• IL reader: src/Core/Test/Rystem.Test.UnitTest/System.Reflection/IlReaderTest.cs
• CSV: src/Core/Test/Rystem.Test.UnitTest/System.Text.Csv/CsvTest.cs
• Minimization: src/Core/Test/Rystem.Test.UnitTest/System.Text.Minimization/MinimizationTest.cs
• Task helpers: src/Core/Test/Rystem.Test.UnitTest/System.Threading.Tasks/TasksTest.cs

The current README is intentionally long because this package covers a lot of independent utilities.