SharpOption

C# representation of a optional value, heavily inspired by F#'s option module and type.

Usage

add a using for SharpOption.Core to start using the Option<T> type.

or you can use SharpOption.Core.ValueOption to use ValueOption<T> value type instead.

Simple usage

using SharpOption.Core;

//...

Option<int> myOption = Option.Some(31);
if (myOption.IsSome) // also has myOption.IsNone property
{
    Console.WriteLine($"my option has Some {myOption.Value} value.");
}
else
{
    Console.WriteLine("my option had a None value.");
}

// instead of if syntax, you can use the .Match(...) method
myOption.Match(
    value => Console.WriteLine($"my option has Some {value} value."),
    () => Console.WriteLine("my option had a None value."),
);

// .Match(...) also supports return
string message = myOption.Match(
    value => $"my option has Some {value} value.",
    () => "my option had a None value.",
);
Console.WriteLine(message);

Option<string> nameOption = Option.None<string>();
string name = Option.DefaultValue(nameOption, "System user");

Simple usage cont.

You can also make use of the using static syntax to reduce the use of Option.<method> throughout your code.

using static SharpOption.Core.Option;

//...

Option<int> myOption1 = Some(31);
Option<int> myOption2 = None<int>();

Option<string> nameOption = None<string>();
Option<string> name = DefaultValue(nameOption, "System user");

Extension method usage

You can start accessing the extension methods by adding a using to SharpOption.Core.Extensions.

using SharpOption.Core.Extensions;

//...

Option<int> myNum = 52.Some();
int? myNullableNum = myNum.ToNullable(); // 52
myNullableNum = null;
Option<int> myNumOfNullable = myNullableNum.OfNullable() // None

F# like usage

See the static class called Option, this class contains F# like option functions.

using SharpOption.Core.Option;

//...

Option<int> myNum1 = Option.Some(52);
Option<int> myNum2 = Option.Some(3);
Option<int> myNumMap = Option.Map(myNum1, myNum2, (n1, n2) => n1 + n2);
Option<int> myNumBind = Option.Bind(myNum1, myNum2, (n1, n2) => Option.Some(n1 + n2));

// please see the Option static class for all methods...

Query syntax

To start using the linq query syntax add a using for SharpOption.Core.Monodic.

using SharpOption.Core.Monodic;

Option<int> op1 =
    from first in Option.Some(43)
    where first > 14
    select first; // will return Some(43)

Option<int> op2 =
    from first in Option.Some(43)
    where first > 50
    select first; // will return None

Option<int> op3 =
    from first in Option.Some(10)
    from second in Option.Some(2)
    select first + second; // will return Some(12)

Option<int> op4 =
    from first in Option.Some(10)
    from second in Option.None<int>()
    select first + second; // will return None

// also supports Task
async Task<Option<int>> GetOptionFromDbAsync(int? value)
{
    await Task.Delay(0);
    Option<int> myOptionFromDb = Option.OfNullable(value);
    return myOptionFromDb;
}

Option<int> op5 = await (
    from first in GetOptionFromDbAsync(15)
    from second in GetOptionFromDbAsync(10)
    select first + second
); // will return Some(25)

Option<int> op6 = await (
    from first in GetOptionFromDbAsync(15)
    from second in GetOptionFromDbAsync(null)
    select first + second
); // will return None

Todo

XML documentation for all public APIs.
Add more linq query operator/keyword support.
Review and fix all comparison/equality functionality for Option and ValueOption.
Json serialization support.
Maybe EntityFrameworkCore support.

Dragwar/SharpOption