feat: initial project commit

src/Results/Errors/AggregateError.cs

@@ -0,0 +1,16 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// An error which is a combination of other errors.
+/// </summary>
+/// <param name="errors">The errors the error consists of.</param>
+public sealed class AggregateError(IEnumerable<Error> errors) : Error
+{
+	/// <summary>
+	/// The errors the error consists of.
+	/// </summary>
+	public IReadOnlyCollection<Error> Errors { get; } = errors.ToList();
+
+	/// <inheritdoc/>
+	public override string Message => string.Join(Environment.NewLine, Errors.Select(error => error.Message));
+}

src/Results/Errors/Error.cs

@@ -0,0 +1,33 @@
+namespace Geekeey.Common.Results;
+
+public abstract class Error
+{
+	/// <summary>
+	/// A statically accessible default "Result has no value." error.
+	/// </summary>
+	internal static Error DefaultValueError { get; } = new StringError("The result has no value.");
+
+	/// <summary>
+	/// The message used to display the error.
+	/// </summary>
+	public abstract string Message { get; }
+
+	/// <summary>
+	/// Gets a string representation of the error. Returns <see cref="Message"/> by default.
+	/// </summary>
+	public override string ToString() => Message;
+
+	/// <summary>
+	/// Implicitly converts a string into a <see cref="StringError"/>.
+	/// </summary>
+	/// <param name="message">The message of the error.</param>
+	public static implicit operator Error(string message)
+		=> new StringError(message);
+
+	/// <summary>
+	/// Implicitly converts an exception into an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="exception">The exception to convert.</param>
+	public static implicit operator Error(Exception exception)
+		=> new ExceptionError(exception);
+}

src/Results/Errors/ExceptionError.cs

@@ -0,0 +1,18 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// An error which is constructed from an exception.
+/// </summary>
+/// <param name="exception">The exception in the error.</param>
+public sealed class ExceptionError(Exception exception) : Error
+{
+	/// <summary>
+	/// The exception in the error.
+	/// </summary>
+	public Exception Exception { get; } = exception;
+
+	/// <summary>
+	/// The exception in the error.
+	/// </summary>
+	public override string Message => Exception.Message;
+}

src/Results/Errors/InvalidOperationError.cs

@@ -0,0 +1,11 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// An error which represents an invalid operation.
+/// </summary>
+/// <param name="message">An optional message describing the operation and why it is invalid.</param>
+public sealed class InvalidOperationError(string? message = null) : Error
+{
+	/// <inheritdoc/>
+	public override string Message => message ?? "Invalid operation.";
+}

src/Results/Errors/NotFoundError.cs

@@ -0,0 +1,17 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// An error which represents something which wasn't found.
+/// </summary>
+/// <param name="key">The key corresponding to the thing which wasn't found.</param>
+/// <param name="message">A message which describes the thing which wasn't found.</param>
+public sealed class NotFoundError(object? key, string message) : Error
+{
+	/// <summary>
+	/// The key corresponding to the thing which wasn't found.
+	/// </summary>
+	public object? Key { get; } = key;
+
+	/// <inheritdoc/>
+	public override string Message => message;
+}

src/Results/Errors/StringError.cs

@@ -0,0 +1,11 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// An error which displays a simple string.
+/// </summary>
+/// <param name="message">The message to display.</param>
+public sealed class StringError(string message) : Error
+{
+	/// <inheritdoc/>
+	public override string Message => message;
+}

src/Results/Exceptions/UnwrapException.cs

@@ -0,0 +1,18 @@
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// The exception is thrown when an <see cref="Result{T}"/> is attempted to be unwrapped contains only a failure value.
+/// </summary>
+public sealed class UnwrapException : Exception
+{
+	/// <summary>
+	/// Creates a new <see cref="UnwrapException"/>.
+	/// </summary>
+	public UnwrapException() : base("Cannot unwrap result because it does not have a value.") { }
+
+	/// <summary>
+	/// Creates a new <see cref="UnwrapException"/>.
+	/// </summary>
+	/// <param name="error">An error message.</param>
+	public UnwrapException(string error) : base(error) { }
+}

src/Results/Extensions/Extensions.Enumerable.cs

@@ -0,0 +1,34 @@
+namespace Geekeey.Common.Results;
+
+public static partial class Extensions
+{
+	/// <summary>
+	/// Turns a sequence of results into a single result containing the success values in the results only if all the
+	/// results have success values.
+	/// </summary>
+	/// <param name="results">The results to turn into a single sequence.</param>
+	/// <typeparam name="T">The type of the success values in the results.</typeparam>
+	/// <returns>A single result containing a sequence of all the success values from the original sequence of results,
+	/// or the first failure value encountered within the sequence.</returns>
+	/// <remarks>
+	/// This method completely enumerates the input sequence before returning and is not lazy. As a consequence of this,
+	/// the sequence within the returned result is an <see cref="IReadOnlyList{T}"/>.
+	/// </remarks>
+	public static Result<IReadOnlyList<T>> Join<T>(this IEnumerable<Result<T>> results)
+	{
+		_ = results.TryGetNonEnumeratedCount(out var count);
+		var list = new List<T>(count);
+
+		foreach (var result in results)
+		{
+			if (!result.TryGetValue(out var value, out var error))
+			{
+				return new Result<IReadOnlyList<T>>(error);
+			}
+
+			list.Add(value);
+		}
+
+		return list;
+	}
+}

src/Results/Extensions/Extensions.Task.cs

@@ -0,0 +1,48 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Runtime.CompilerServices;
+
+namespace Geekeey.Common.Results;
+
+[ExcludeFromCodeCoverage]
+public static partial class Extensions
+{
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async Task<Result<TNew>> Map<T, TNew>(this ValueTask<Result<T>> result,
+		Func<T, TNew> func)
+		=> (await result).Map(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async ValueTask<Result<TNew>> Map<T, TNew>(this Task<Result<T>> result,
+		Func<T, TNew> func)
+		=> (await result).Map(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async ValueTask<Result<TNew>> Map<T, TNew>(this ValueTask<Result<T>> result,
+		Func<T, ValueTask<TNew>> func)
+		=> await (await result).MapAsync(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async Task<Result<TNew>> Map<T, TNew>(this Task<Result<T>> result,
+		Func<T, ValueTask<TNew>> func)
+		=> await (await result).MapAsync(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async ValueTask<Result<TNew>> Then<T, TNew>(this ValueTask<Result<T>> result,
+		Func<T, Result<TNew>> func)
+		=> (await result).Then(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async Task<Result<TNew>> Then<T, TNew>(this Task<Result<T>> result,
+		Func<T, Result<TNew>> func)
+		=> (await result).Then(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async ValueTask<Result<TNew>> Then<T, TNew>(this ValueTask<Result<T>> result,
+		Func<T, ValueTask<Result<TNew>>> func)
+		=> await (await result).ThenAsync(func);
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining)]
+	public static async Task<Result<TNew>> Then<T, TNew>(this Task<Result<T>> result,
+		Func<T, ValueTask<Result<TNew>>> func)
+		=> await (await result).ThenAsync(func);
+}

src/Results/Prelude.cs

@@ -0,0 +1,92 @@
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// A class containing various utility methods, a 'prelude' to the rest of the library.
+/// </summary>
+/// <remarks>
+/// This class is meant to be imported statically, e.g. <c>using static Geekeey.Common.Results.Prelude;</c>.
+/// Recommended to be imported globally via a global using statement.
+/// </remarks>
+public static class Prelude
+{
+	/// <summary>
+	/// Creates a result containing an success value.
+	/// </summary>
+	/// <typeparam name="T">The type of the success value.</typeparam>
+	/// <param name="value">The success value to create the result from.</param>
+	[Pure]
+	public static Result<T> Success<T>(T value) => new(value);
+
+	/// <summary>
+	/// Creates a result containing a failure value.
+	/// </summary>
+	/// <typeparam name="T">The type of an success value in the result.</typeparam>
+	/// <param name="error">The failure value to create the result from.</param>
+	[Pure]
+	public static Result<T> Failure<T>(Error error) => new(error);
+
+	/// <summary>
+	/// Tries to execute a function and return the result. If the function throws an exception, the exception will be
+	/// returned wrapped in an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <typeparam name="T">The type the function returns.</typeparam>
+	/// <param name="function">The function to try execute.</param>
+	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
+	/// exception thrown by the function.</returns>
+	[Pure]
+	public static Result<T> Try<T>(Func<T> function)
+	{
+		try
+		{
+			return new Result<T>(function());
+		}
+		catch (Exception exception)
+		{
+			return new Result<T>(new ExceptionError(exception));
+		}
+	}
+
+	/// <summary>
+	/// Tries to execute an asynchronous function and return the result. If the function throws an exception, the
+	/// exception will be returned wrapped in an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <typeparam name="T">The type the function returns.</typeparam>
+	/// <param name="function">The function to try execute.</param>
+	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
+	/// exception thrown by the function.</returns>
+	[Pure]
+	public static async ValueTask<Result<T>> TryAsync<T>(Func<ValueTask<T>> function)
+	{
+		try
+		{
+			return new Result<T>(await function());
+		}
+		catch (Exception exception)
+		{
+			return new Result<T>(new ExceptionError(exception));
+		}
+	}
+
+	/// <summary>
+	/// Tries to execute an asynchronous function and return the result. If the function throws an exception, the
+	/// exception will be returned wrapped in an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <typeparam name="T">The type the function returns.</typeparam>
+	/// <param name="function">The function to try execute.</param>
+	/// <returns>A result containing the return value of the function or an <see cref="ExceptionError"/> containing the
+	/// exception thrown by the function.</returns>
+	[Pure]
+	public static async Task<Result<T>> TryAsync<T>(Func<Task<T>> function)
+	{
+		try
+		{
+			return new Result<T>(await function());
+		}
+		catch (Exception exception)
+		{
+			return new Result<T>(new ExceptionError(exception));
+		}
+	}
+}

src/Results/Project.props

@@ -0,0 +1,5 @@
+<Project>
+  <ItemGroup Condition="'$(ImplicitUsings)' == 'enable'">
+    <Using Include="Geekeey.Common.Results.Prelude" Static="true" />
+  </ItemGroup>
+</Project>

src/Results/Result.Conversion.cs

@@ -0,0 +1,36 @@
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Implicitly constructs a result from a success value.
+	/// </summary>
+	/// <param name="value">The value to construct the result from.</param>
+	[Pure]
+	public static implicit operator Result<T>(T value) => new(value);
+
+	/// <summary>
+	/// Implicitly constructs a result from a failure value.
+	/// </summary>
+	/// <param name="error">The error to construct the result from.</param>
+	[Pure]
+	public static implicit operator Result<T>(Error error) => new(error);
+
+	/// <summary>
+	/// Unwraps the success value of the result. Throws an <see cref="UnwrapException"/> if the result is a failure.
+	/// </summary>
+	/// <remarks>
+	/// This call is <b>unsafe</b> in the sense that it might intentionally throw an exception. Please only use this
+	/// call if the caller knows that this operation is safe, or that an exception is acceptable to be thrown.
+	/// </remarks>
+	/// <returns>The success value of the result.</returns>
+	/// <exception cref="UnwrapException">The result is not a success.</exception>
+	[Pure]
+	public T Unwrap() => IsSuccess ? Value! : throw new UnwrapException();
+
+	/// <inheritdoc cref="Unwrap"/>
+	[Pure]
+	public static explicit operator T(Result<T> result) => result.Unwrap();
+}

src/Results/Result.Equality.cs

@@ -0,0 +1,115 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Contracts;
+using System.Numerics;
+
+namespace Geekeey.Common.Results;
+
+public readonly partial struct Result<T> : IEquatable<Result<T>>, IEquatable<T>,
+	IEqualityOperators<Result<T>, Result<T>, bool>, IEqualityOperators<Result<T>, T, bool>
+{
+	/// <summary>
+	/// Checks whether the result is equal to another result. Results are equal if both results are success values and
+	/// the success values are equal, or if both results are failures.
+	/// </summary>
+	/// <param name="other">The result to check for equality with the current result.</param>
+	[Pure]
+	public bool Equals(Result<T> other)
+		=> Equals(this, other, EqualityComparer<T>.Default);
+
+	/// <summary>
+	/// Checks whether the result is equal to another result. Results are equal if both results are success values and
+	/// the success values are equal, or if both results are failures.
+	/// </summary>
+	/// <param name="other">The result to check for equality with the current result.</param>
+	/// <param name="comparer">The equality comparer to use for comparing values.</param>
+	[Pure]
+	public bool Equals(Result<T> other, IEqualityComparer<T> comparer)
+		=> Equals(this, other, comparer);
+
+	/// <summary>
+	/// Checks whether the result is a success value and the success value is equal to another value.
+	/// </summary>
+	/// <param name="other">The value to check for equality with the success value of the result.</param>
+	[Pure]
+	public bool Equals(T? other)
+		=> Equals(this, other, EqualityComparer<T>.Default);
+
+	/// <summary>
+	/// Checks whether the result is a success value and the success value is equal to another value using a specified
+	/// equality comparer.
+	/// </summary>
+	/// <param name="other">The value to check for equality with the success value of the result.</param>
+	/// <param name="comparer">The equality comparer to use for comparing values.</param>
+	[Pure]
+	public bool Equals(T? other, IEqualityComparer<T> comparer)
+		=> Equals(this, other, comparer);
+
+	/// <inheritdoc/>
+	[Pure]
+	public override bool Equals(object? other)
+		=> other is T x && Equals(x) || other is Result<T> r && Equals(r);
+
+	/// <inheritdoc/>
+	[Pure]
+	public override int GetHashCode()
+		=> GetHashCode(this, EqualityComparer<T>.Default);
+
+	internal static bool Equals(Result<T> a, Result<T> b, IEqualityComparer<T> comparer)
+	{
+		if (!a._success || !b._success) return !a._success && !b._success;
+		if (a.Value is null || b.Value is null) return a.Value is null && b.Value is null;
+		return comparer.Equals(a.Value, b.Value);
+	}
+
+	internal static bool Equals(Result<T> a, T? b, IEqualityComparer<T> comparer)
+	{
+		if (!a._success) return false;
+		if (a.Value is null || b is null) return a.Value is null && b is null;
+		return comparer.Equals(a.Value, b);
+	}
+
+	internal static int GetHashCode(Result<T> result, IEqualityComparer<T> comparer)
+	{
+		if (result is { _success: true, Value: not null })
+			return comparer.GetHashCode(result.Value);
+		return 0;
+	}
+
+	/// <summary>
+	/// Checks whether two results are equal. Results are equal if both results are success values and the success
+	/// values are equal, or if both results are failures.
+	/// </summary>
+	/// <param name="a">The first result to compare.</param>
+	/// <param name="b">The second result to compare.</param>
+	[Pure]
+	[ExcludeFromCodeCoverage]
+	public static bool operator ==(Result<T> a, Result<T> b) => a.Equals(b);
+
+	/// <summary>
+	/// Checks whether two results are not equal. Results are equal if both results are success values and the success
+	/// values are equal, or if both results are failures.
+	/// </summary>
+	/// <param name="a">The first result to compare.</param>
+	/// <param name="b">The second result to compare.</param>
+	[Pure]
+	[ExcludeFromCodeCoverage]
+	public static bool operator !=(Result<T> a, Result<T> b) => !a.Equals(b);
+
+	/// <summary>
+	/// Checks whether a result is a success value and the success value is equal to another value.
+	/// </summary>
+	/// <param name="a">The result to compare.</param>
+	/// <param name="b">The value to check for equality with the success value in the result.</param>
+	[Pure]
+	[ExcludeFromCodeCoverage]
+	public static bool operator ==(Result<T> a, T? b) => a.Equals(b);
+
+	/// <summary>
+	/// Checks whether a result either does not have a value, or the value is not equal to another value.
+	/// </summary>
+	/// <param name="a">The result to compare.</param>
+	/// <param name="b">The value to check for inequality with the success value in the result.</param>
+	[Pure]
+	[ExcludeFromCodeCoverage]
+	public static bool operator !=(Result<T> a, T? b) => !a.Equals(b);
+}

src/Results/Result.Matching.cs

@@ -0,0 +1,91 @@
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Matches over the success value or failure value of the result and returns another value. Can be conceptualized
+	/// as an exhaustive <c>switch</c> expression matching all possible values of the type.
+	/// </summary>
+	/// <typeparam name="TResult">The type to return from the match.</typeparam>
+	/// <param name="success">The function to apply to the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to apply to the failure value of the result if the result is a failure.</param>
+	/// <returns>The result of applying either <paramref name="success"/> or <paramref name="failure"/> on the success
+	/// value or failure value of the result.</returns>
+	[Pure]
+	public TResult Match<TResult>(Func<T, TResult> success, Func<Error, TResult> failure)
+		=> _success ? success(Value!) : failure(Error!);
+
+	/// <summary>
+	/// Matches over the success value or failure value of the result and invokes an effectful action onto the success
+	/// value or failure value. Can be conceptualized as an exhaustive <c>switch</c> statement matching all possible
+	/// values of the type.
+	/// </summary>
+	/// <param name="success">The function to call with the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to call with the failure value of the result if the result is a failure.</param>
+	public void Switch(Action<T> success, Action<Error> failure)
+	{
+		if (_success) success(Value!);
+		else failure(Error!);
+	}
+}
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Asynchronously matches over the success value or failure value of the result and returns another value. Can be
+	/// conceptualized as an exhaustive <c>switch</c> expression matching all possible values of the type.
+	/// </summary>
+	/// <typeparam name="TResult">The type to return from the match.</typeparam>
+	/// <param name="success">The function to apply to the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to apply to the failure value of the result if the result is a failure.</param>
+	/// <returns>A task completing with the result of applying either <paramref name="success"/> or
+	/// <paramref name="failure"/> on the success value or failure value of the result.</returns>
+	[Pure]
+	public async ValueTask<TResult> MatchAsync<TResult>(Func<T, ValueTask<TResult>> success, Func<Error, ValueTask<TResult>> failure)
+		=> _success ? await success(Value!) : await failure(Error!);
+
+	/// <summary>
+	/// Asynchronously matches over the success value or failure value of the result and invokes an effectful action
+	/// onto the success value or the failure value. Can be conceptualized as an exhaustive <c>switch</c> statement
+	/// matching all possible values of the type.
+	/// </summary>
+	/// <param name="success">The function to call with the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to call with the failure value of the result if the result is a failure.</param>
+	public async ValueTask SwitchAsync(Func<T, ValueTask> success, Func<Error, ValueTask> failure)
+	{
+		if (_success) await success(Value!);
+		else await failure(Error!);
+	}
+}
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Asynchronously matches over the success value or failure value of the result and returns another value. Can be
+	/// conceptualized as an exhaustive <c>switch</c> expression matching all possible values of the type.
+	/// </summary>
+	/// <typeparam name="TResult">The type to return from the match.</typeparam>
+	/// <param name="success">The function to apply to the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to apply to the failure value of the result if the result is a failure.</param>
+	/// <returns>A task completing with the result of applying either <paramref name="success"/> or
+	/// <paramref name="failure"/> on the success value or failure value of the result.</returns>
+	[Pure]
+	public async Task<TResult> MatchAsync<TResult>(Func<T, Task<TResult>> success, Func<Error, Task<TResult>> failure)
+		=> _success ? await success(Value!) : await failure(Error!);
+
+	/// <summary>
+	/// Asynchronously matches over the success value or failure value of the result and invokes an effectful action
+	/// onto the success value or failure value. Can be conceptualized as an exhaustive <c>switch</c> statement matching
+	/// all possible values of
+	/// the type.
+	/// </summary>
+	/// <param name="success">The function to call with the success value of the result if the result is a success.</param>
+	/// <param name="failure">The function to call with the failure value of the result if the result is a failure.</param>
+	public async Task SwitchAsync(Func<T, Task> success, Func<Error, Task> failure)
+	{
+		if (_success) await success(Value!);
+		else await failure(Error!);
+	}
+}

src/Results/Result.Transform.cs

@@ -0,0 +1,335 @@
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Maps the success value of the result using a mapping function, or does nothing if the result is a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A new result containing either the mapped success value or the failure value of the original
+	/// result.</returns>
+	[Pure]
+	public Result<TNew> Map<TNew>(Func<T, TNew> func)
+		=> _success ? new Result<TNew>(func(Value!)) : new Result<TNew>(Error!);
+
+	/// <summary>
+	/// Tries to map the success value of the result using a mapping function, or does nothing if the result is a
+	/// failure. If the mapping function throws an exception, the exception will be returned wrapped in an
+	/// <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A new result containing either the mapped value, the exception thrown by <paramref name="func"/>
+	/// wrapped in an <see cref="ExceptionError"/>, or the failure value of the original result.</returns>
+	[Pure]
+	public Result<TNew> TryMap<TNew>(Func<T, TNew> func)
+	{
+		try
+		{
+			return Map(func);
+		}
+		catch (Exception exception)
+		{
+			return new Result<TNew>(new ExceptionError(exception));
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result to a new result using a mapping function, or does nothing if the result is
+	/// a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A result which is either the mapped result or a new result containing the failure value of the original
+	/// result.</returns>
+	[Pure]
+	public Result<TNew> Then<TNew>(Func<T, Result<TNew>> func)
+		=> _success ? func(Value!) : new Result<TNew>(Error!);
+
+	/// <summary>
+	/// Tries to map the success value of the result to a new result using a mapping function, or does nothing if the result
+	/// is a failure. If the mapping function throws an exception, the exception will be returned wrapped in an
+	/// <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A result which is either the mapped result, the exception thrown by <paramref name="func"/> wrapped in
+	/// an <see cref="ExceptionError"/>, or a new result containing the failure value of the original result.</returns>
+	[Pure]
+	public Result<TNew> ThenTry<TNew>(Func<T, Result<TNew>> func)
+	{
+		try
+		{
+			return Then(func);
+		}
+		catch (Exception exception)
+		{
+			return new Result<TNew>(new ExceptionError(exception));
+		}
+	}
+}
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Maps the success value of the result using an asynchronous mapping function, or does nothing if the result is
+	/// a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="ValueTask{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result and constructing a new result containing the mapped value, or completes
+	/// synchronously by returning a new result containing the failure value of the original result.</returns>
+	[Pure]
+	public ValueTask<Result<TNew>> MapAsync<TNew>(Func<T, ValueTask<TNew>> func)
+	{
+		if (!_success) return ValueTask.FromResult(new Result<TNew>(Error!));
+
+		var task = func(Value!);
+		return CreateResult(task);
+
+		static async ValueTask<Result<TNew>> CreateResult(ValueTask<TNew> task)
+		{
+			var value = await task;
+			return new Result<TNew>(value);
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result using an asynchronous mapping function, or does nothing if the result is a
+	/// failure. If the mapping function throws an exception, the exception will be returned wrapped in an
+	/// <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="ValueTask{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result and constructing a new result containing the mapped value, returning any exception
+	/// thrown by <paramref name="func"/> wrapped in an <see cref="ExceptionError"/> or completes synchronously by
+	/// returning a new result containing the failure value of the original result.</returns>
+	[Pure]
+	public ValueTask<Result<TNew>> TryMapAsync<TNew>(Func<T, ValueTask<TNew>> func)
+	{
+		if (!_success) return ValueTask.FromResult(new Result<TNew>(Error!));
+
+		try
+		{
+			var task = func(Value!);
+			return CreateResult(task);
+		}
+		catch (Exception exception)
+		{
+			return ValueTask.FromResult(new Result<TNew>(new ExceptionError(exception)));
+		}
+
+		static async ValueTask<Result<TNew>> CreateResult(ValueTask<TNew> task)
+		{
+			try
+			{
+				var value = await task;
+				return new Result<TNew>(value);
+			}
+			catch (Exception exception)
+			{
+				return new Result<TNew>(new ExceptionError(exception));
+			}
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result to a new result using an asynchronous mapping function, or does nothing if
+	/// the result is a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="ValueTask{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result, or completes synchronously by returning a new result containing the failure
+	/// value of the original result.</returns>
+	[Pure]
+	public ValueTask<Result<TNew>> ThenAsync<TNew>(Func<T, ValueTask<Result<TNew>>> func)
+	{
+		if (!_success) return ValueTask.FromResult(new Result<TNew>(Error!));
+
+		var task = func(Value!);
+		return CreateResult(task);
+
+		static async ValueTask<Result<TNew>> CreateResult(ValueTask<Result<TNew>> task)
+		{
+			var result = await task;
+			return result;
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result to a new result using an asynchronous mapping function, or does nothing if
+	/// the result is a failure. If the mapping function throws an exception, the exception will be returned wrapped in
+	/// an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="ValueTask{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result, returning any exception thrown by <paramref name="func"/> wrapped in an
+	/// <see cref="ExceptionError"/>, or completes synchronously by returning a new result containing the failure value
+	/// of the original result.</returns>
+	[Pure]
+	public ValueTask<Result<TNew>> ThenTryAsync<TNew>(Func<T, ValueTask<Result<TNew>>> func)
+	{
+		if (!_success) return ValueTask.FromResult(new Result<TNew>(Error!));
+
+		try
+		{
+			var task = func(Value!);
+			return CreateResult(task);
+		}
+		catch (Exception exception)
+		{
+			return ValueTask.FromResult(new Result<TNew>(new ExceptionError(exception)));
+		}
+
+		static async ValueTask<Result<TNew>> CreateResult(ValueTask<Result<TNew>> task)
+		{
+			try
+			{
+				var value = await task;
+				return value;
+			}
+			catch (Exception exception)
+			{
+				return new Result<TNew>(new ExceptionError(exception));
+			}
+		}
+	}
+}
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Maps the success value of the result using an asynchronous mapping function, or does nothing if the result is
+	/// a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="Task{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result and constructing a new result containing the mapped value, or completes
+	/// synchronously by returning a new result containing the failure value of the original result.</returns>
+	[Pure]
+	public Task<Result<TNew>> MapAsync<TNew>(Func<T, Task<TNew>> func)
+	{
+		if (!_success) return Task.FromResult(new Result<TNew>(Error!));
+
+		var task = func(Value!);
+		return CreateResult(task);
+
+		static async Task<Result<TNew>> CreateResult(Task<TNew> task)
+		{
+			var value = await task;
+			return new Result<TNew>(value);
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result using an asynchronous mapping function, or does nothing if the result is a
+	/// failure. If the mapping function throws an exception, the exception will be returned wrapped in an
+	/// <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="Task{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result and constructing a new result containing the mapped value, returning any exception
+	/// thrown by <paramref name="func"/> wrapped in an <see cref="ExceptionError"/> or completes synchronously by
+	/// returning a new result containing the failure value of the original result.</returns>
+	[Pure]
+	public Task<Result<TNew>> TryMapAsync<TNew>(Func<T, Task<TNew>> func)
+	{
+		if (!_success) return Task.FromResult(new Result<TNew>(Error!));
+
+		try
+		{
+			var task = func(Value!);
+			return CreateResult(task);
+		}
+		catch (Exception exception)
+		{
+			return Task.FromResult(new Result<TNew>(new ExceptionError(exception)));
+		}
+
+		static async Task<Result<TNew>> CreateResult(Task<TNew> task)
+		{
+			try
+			{
+				var value = await task;
+				return new Result<TNew>(value);
+			}
+			catch (Exception exception)
+			{
+				return new Result<TNew>(new ExceptionError(exception));
+			}
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result to a new result using an asynchronous mapping function, or does nothing if
+	/// the result is a failure.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="Task{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result, or completes synchronously by returning a new result containing the failure
+	/// value of the original result.</returns>
+	[Pure]
+	public Task<Result<TNew>> ThenAsync<TNew>(Func<T, Task<Result<TNew>>> func)
+	{
+		if (!_success) return Task.FromResult(new Result<TNew>(Error!));
+
+		var task = func(Value!);
+		return CreateResult(task);
+
+		static async Task<Result<TNew>> CreateResult(Task<Result<TNew>> task)
+		{
+			var result = await task;
+			return result;
+		}
+	}
+
+	/// <summary>
+	/// Maps the success value of the result to a new result using an asynchronous mapping function, or does nothing if
+	/// the result is a failure. If the mapping function throws an exception, the exception will be returned wrapped in
+	/// an <see cref="ExceptionError"/>.
+	/// </summary>
+	/// <param name="func">The function used to map the success value to a new result.</param>
+	/// <typeparam name="TNew">The type of the new value.</typeparam>
+	/// <returns>A <see cref="Task{T}"/> which either completes asynchronously by invoking the mapping function on
+	/// the success value of the result, returning any exception thrown by <paramref name="func"/> wrapped in an
+	/// <see cref="ExceptionError"/>, or completes synchronously by returning a new result containing the failure value
+	/// of the original result.</returns>
+	[Pure]
+	public Task<Result<TNew>> ThenTryAsync<TNew>(Func<T, Task<Result<TNew>>> func)
+	{
+		if (!_success) return Task.FromResult(new Result<TNew>(Error!));
+
+		try
+		{
+			var task = func(Value!);
+			return CreateResult(task);
+		}
+		catch (Exception exception)
+		{
+			return Task.FromResult(new Result<TNew>(new ExceptionError(exception)));
+		}
+
+		static async Task<Result<TNew>> CreateResult(Task<Result<TNew>> task)
+		{
+			try
+			{
+				var value = await task;
+				return value;
+			}
+			catch (Exception exception)
+			{
+				return new Result<TNew>(new ExceptionError(exception));
+			}
+		}
+	}
+}

src/Results/Result.Unbox.cs

@@ -0,0 +1,63 @@
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+public readonly partial struct Result<T>
+{
+	/// <summary>
+	/// Tries to get the success value from the result.
+	/// </summary>
+	/// <param name="value">The success value of the result.</param>
+	/// <returns>Whether the result has success value.</returns>
+	[Pure]
+	public bool TryGetValue([MaybeNullWhen(false)] out T value)
+	{
+		value = Value!;
+
+		return _success;
+	}
+
+	/// <summary>
+	/// Tries to get the success value from the result.
+	/// </summary>
+	/// <param name="value">The success value of the result.</param>
+	/// <param name="error">The failure value of the result.</param>
+	/// <returns>Whether the result has a success value.</returns>
+	[Pure]
+	public bool TryGetValue([MaybeNullWhen(false)] out T value, [MaybeNullWhen(true)] out Error error)
+	{
+		value = Value!;
+		error = !_success ? Error : null!;
+
+		return _success;
+	}
+
+	/// <summary>
+	/// Tries to get the failure value from the result.
+	/// </summary>
+	/// <param name="error">The failure value of the result.</param>
+	/// <returns>Whether the result has a failure value.</returns>
+	[Pure]
+	public bool TryGetError([MaybeNullWhen(false)] out Error error)
+	{
+		error = !_success ? Error : null!;
+
+		return !_success;
+	}
+
+	/// <summary>
+	/// Tries to get the failure value from the result.
+	/// </summary>
+	/// <param name="error">The failure value of the result.</param>
+	/// <param name="value">The success value of the result.</param>
+	/// <returns>Whether the result a failure value.</returns>
+	[Pure]
+	public bool TryGetError([MaybeNullWhen(false)] out Error error, [MaybeNullWhen(true)] out T value)
+	{
+		error = !_success ? Error : null!;
+		value = Value!;
+
+		return !_success;
+	}
+}

src/Results/Result.cs

@@ -0,0 +1,76 @@
+using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
+using System.Diagnostics.Contracts;
+
+namespace Geekeey.Common.Results;
+
+/// <summary>
+/// A type which contains either a success value or a failure value, which is represented by an <see cref="Error"/>.
+/// </summary>
+/// <typeparam name="T">The type of the success value.</typeparam>
+[DebuggerTypeProxy(typeof(Result<>.ResultDebugProxy))]
+public readonly partial struct Result<T>
+{
+	private readonly bool _success;
+
+	private readonly T? _value;
+	private readonly Error? _error;
+
+	/// <summary>
+	/// Creates a new result with an success value.
+	/// </summary>
+	/// <param name="value">The success value.</param>
+	public Result(T value)
+	{
+		_success = true;
+		_value = value;
+		_error = default;
+	}
+
+	/// <summary>
+	/// Creates a new result with an failure value.
+	/// </summary>
+	/// <param name="error">The error of the result.</param>
+	public Result(Error error)
+	{
+		_success = false;
+		_value = default;
+		_error = error;
+	}
+
+	internal T? Value => _value;
+
+	internal Error? Error => _success ? null : (_error ?? Error.DefaultValueError);
+
+	/// <summary>
+	/// Whether the result is a success.
+	/// </summary>
+	/// <remarks>
+	/// This is always the inverse of <see cref="IsFailure"/> but is more specific about intent.
+	/// </remarks>
+	[MemberNotNullWhen(true, nameof(Value))]
+	public bool IsSuccess => _success;
+
+	/// <summary>
+	/// Whether the result is a failure.
+	/// </summary>
+	/// <remarks>
+	/// This is always the inverse of <see cref="IsSuccess"/> but is more specific about intent.
+	/// </remarks>
+	[MemberNotNullWhen(true, nameof(Error))]
+	public bool IsFailure => !_success;
+
+	/// <summary>
+	/// Gets a string representation of the result.
+	/// </summary>
+	[Pure]
+	public override string ToString()
+		=> _success ? $"Success {{ {Value} }}" : $"Failure {{ {Error} }}";
+
+	private sealed class ResultDebugProxy(Result<T> result)
+	{
+		public bool IsSuccess => result.IsSuccess;
+
+		public object? Value => result.IsSuccess ? result.Value : result.Error;
+	}
+}

src/Results/Results.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <InternalsVisibleTo Include="$(AssemblyName).Tests" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <None Include=".\package-readme.md" Pack="true" PackagePath="\" />
+    <None Include="Project.props" Pack="true" PackagePath="build\$(AssemblyName).props" />
+  </ItemGroup>
+</Project>

src/Results/package-readme.md

@@ -0,0 +1,2 @@
+Result is a simple yet powerful [result type](https://doc.rust-lang.org/std/result/) implementation for C#, containing a
+variety of utilities and standard functions for working with result types and integrating them into the rest of C#.