public class Product
{
    [GraphQLType(typeof(IdType))]
    public int Id { get; set; }
}

public class Query
{
    public Product GetProduct([GraphQLType(typeof(IdType))] int id)
    {
        // Omitted code for brevity
    }
}

services
   .AddGraphQLServer()
   .AddType(new UuidType('D'));

object foo = context.ArgumentValue<object>("bar");
Foo foo = context.ArgumentValue<Foo>("bar");

ValueKind kind = context.ArgumentKind("bar");

public enum ValueKind
{
    String,
    Integer,
    Float,
    Boolean,
    Enum,
    Object,
    Null
}

[GraphQLType(typeof(EmailAddressType))]
public string GetEmail() => "[email protected]";

public class Query
{
    public Duration GetDuration() => Duration.FromMinutes(3);
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services
            .AddGraphQLServer()
            .AddQueryType<Query>()
            .AddType<DurationType>();
    }
}

services
    .AddGraphQLServer()
    .BindRuntimeType<string, StringType>();

services
    .AddGraphQLServer()
    .BindRuntimeType<byte[], ByteArrayType>();

public class Query
{
    public OffsetDateTime GetDateTime(OffsetDateTime offsetDateTime)
    {
        return offsetDateTime;
    }
}

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services
            .AddGraphQLServer()
            .AddQueryType<Query>()
            .BindRuntimeType<OffsetDateTime, DateTimeType>()
            .AddTypeConverter<OffsetDateTime, DateTimeOffset>(
                x => x.ToDateTimeOffset())
            .AddTypeConverter<DateTimeOffset, OffsetDateTime>(
                x => OffsetDateTime.FromDateTimeOffset(x));
    }
}

services
   .AddGraphQLServer()
   .AddType(new UuidType('D'));

public sealed class CreditCardNumberType : ScalarType<string, StringValueNode>
{
    private readonly ICreditCardValidator _validator;

    // we can inject services that have been registered
    // with the DI container
    public CreditCardNumberType(ICreditCardValidator validator)
        : base("CreditCardNumber")
    {
        _validator = validator;

        Description = "Represents a credit card number";
    }

    // is another StringValueNode an instance of this scalar
    protected override bool IsInstanceOfType(StringValueNode valueSyntax)
        => IsInstanceOfType(valueSyntax.Value);

    // is another string .NET type an instance of this scalar
    protected override bool IsInstanceOfType(string runtimeValue)
        => _validator.ValidateCreditCard(runtimeValue);

    public override IValueNode ParseResult(object? resultValue)
        => ParseValue(resultValue);

    // define how a value node is parsed to the string .NET type
    protected override string ParseLiteral(StringValueNode valueSyntax)
        => valueSyntax.Value;

    // define how the string .NET type is parsed to a value node
    protected override StringValueNode ParseValue(string runtimeValue)
        => new StringValueNode(runtimeValue);

    public override bool TryDeserialize(object? resultValue,
        out object? runtimeValue)
    {
        runtimeValue = null;

        if (resultValue is string s && _validator.ValidateCreditCard(s))
        {
            runtimeValue = s;
            return true;
        }

        return false;
    }

    public override bool TrySerialize(object? runtimeValue,
        out object? resultValue)
    {
        resultValue = null;

        if (runtimeValue is string s && _validator.ValidateCreditCard(s))
        {
            resultValue = s;
            return true;
        }

        return false;
    }
}

public class CreditCardNumberType : ScalarType
{
    private readonly ICreditCardValidator _validator;

    public CreditCardNumberType(ICreditCardValidator validator)
        : base("CreditCardNumber")
    {
        _validator = validator;

        Description = "Represents a credit card number";
    }

    // define which .NET type represents your type
    public override Type RuntimeType { get; } = typeof(string);

    // define which value nodes this type can be parsed from
    public override bool IsInstanceOfType(IValueNode valueSyntax)
    {
        if (valueSyntax == null)
        {
            throw new ArgumentNullException(nameof(valueSyntax));
        }

        return valueSyntax is StringValueNode stringValueNode &&
            _validator.ValidateCreditCard(stringValueNode.Value);
    }

    // define how a value node is parsed to the native .NET type
    public override object ParseLiteral(IValueNode valueSyntax,
        bool withDefaults = true)
    {
        if (valueSyntax is StringValueNode stringLiteral &&
            _validator.ValidateCreditCard(stringLiteral.Value))
        {
            return stringLiteral.Value;
        }

        throw new SerializationException(
            "The specified value has to be a credit card number in the format "
                + "XXXX XXXX XXXX XXXX",
            this);
    }

    // define how the .NET type is parsed to a value node
    public override IValueNode ParseValue(object? runtimeValue)
    {
        if (runtimeValue is string s &&
            _validator.ValidateCreditCard(s))
        {
            return new StringValueNode(null, s, false);
        }

        throw new SerializationException(
            "The specified value has to be a credit card number in the format "
                + "XXXX XXXX XXXX XXXX",
            this);
    }

    public override IValueNode ParseResult(object? resultValue)
    {
        if (resultValue is string s &&
            _validator.ValidateCreditCard(s))
        {
            return new StringValueNode(null, s, false);
        }

        throw new SerializationException(
            "The specified value has to be a credit card number in the format "
                + "XXXX XXXX XXXX XXXX",
            this);
    }

    public override bool TrySerialize(object? runtimeValue,
        out object? resultValue)
    {
        resultValue = null;

        if (runtimeValue is string s &&
            _validator.ValidateCreditCard(s))
        {
            resultValue = s;
            return true;
        }

        return false;
    }

    public override bool TryDeserialize(object? resultValue,
        out object? runtimeValue)
    {
        runtimeValue = null;

        if (resultValue is string s &&
            _validator.ValidateCreditCard(s))
        {
            runtimeValue = s;
            return true;
        }

        return false;
    }
}