NX

C# Necessary eXtensions library.

• ML-style Option type w/ OCaml's Option module
• OCaml's Seq module (for IEnumerable)
• Using class; monadic IDisposable/using wrapper
• try/catch wrapping integrated w/ Option
• and more

Classes & Structs

struct Option<T>, static class Option

Represents optional value, which can be used to eliminate the null.

Any null occurrence inside the Option world will be treated as an Option.None, so there is no worry for the NullReferenceException.

Respects OCaml's Option module.

example:

bool enabled = filename
    .Try(File.ReadAllText)
    .Map(MySettingFormat.Parse)
    .Map(x => x.Flags["enabled"])
    .Default(false); // if None, return false instead

If the operation can throw an exception and you want to ignore it, use Try (TryMap) instead of Map.

You can use MatchEx to catch the exception then.

Option.Try(TakeSomething)
    .MatchEx(
        x => Console.WriteLine("got something: {0}", x),
        ex => Console.WriteLine("error: {0}", ex.Message),
        () => Console.WriteLine("got nothing.")
    );

In addition, this can be used to set the default value of optional arguments in methods, as Option<T> is struct.

void Hello(Option<string> name = default(Option<string>))
{
    name.Match(
        x => Console.WriteLine("Hello, {0}."),
        () => Console.WriteLine("Hello.")
    );
}

Hello();
Hello("World"); // supports implicit cast from T to Option<T>

Contains Map, Try, Match, Default, and so on.

static class Seq

Extensions for IEnumerable<T>.

Respects OCaml's Seq module.

example:

classes
    .Map(x => x.Students)
    .Flatten()
    .Find(x => x.Name == "John")
    .Match(
        x => GiveMoney(x, 100),
        () => Console.WriteLine("John not found!")
    );

Find, Head, Tail and Nth will return None instead of throwing exceptions, when the desired element doesn't exist.

var john1 = people.FirstOrDefault(x => x.Name == "John");
if (john1 == null)
    return false;
else
    return john1.Money > 100 && Order(john1, OrderType.BuyAnApple).Succeed;

---

return people
    .Find(x => x.Name == "John")
    .Filter(x => x.Money > 100) 
    .Map(x => Order(x, OrderType.BuyAnApple).Succeed)
    .Default(false);

Contains Map, Filter, FoldR, Find, Iter, JoinToString and so on.

class Using<T>, static class Using

Wraps IDisposable<T> with psuedo-monadic style.

example:

string s =
    from x in File.OpenRead("a.txt").Use()
    from y in new StreamReader(x).Use()
    select y.ReadToEnd();

Contains Use, Map, SelectMany, and so on.

class Diff, class DiffItem, enum DiffState

Compares two IEnumerable<T> sequences and show which item is added or removed.

example:

var s1 = New.Seq(1, 2, 3, 4, 5);
var s2 = New.Seq(1, 3, 0, 4, 6);
var diff = s1.Diff(s2);
diff.Print();
//  1
//- 2
//  3
//+ 0
//  4
//- 5
//+ 6

static class EnumNX

Generic Enum.Parse.

static class StreamNX

Writes string to stream directly.

class TComparer<T>, class TEquialityComparer<T>

Grabs IComparer<T> from Func<T, T, int>.

static class New

Initialises T[] and IEnumerable<T> with params T[].

static class Shell

Executes shell command with less typing.

example:

var foo = Shell.Eval("echo", "foo");
Shell.Execute("vim", "a.txt");

static class ConsoleNX

ColoredWrite and ColoredWriteLine.