[Hakeashar]

I would love to see pattern matching and at least some kind of tuple support. I don't know if it's ever going to happen in C# though...

The `using` static is actually really good news. I have seen people who seem to be really mad about it, but sometimes it would be nice to have, for example:

    // Something like Scala's 'Predef'
    public static class Id<T>
    {
	public static Func<T, T> Identity { get {  return x => x; } }
    }

and then do:

   using Id;

   var grouped = list.GroupBy(Identity);

Considering you can already open modules in F# (which are compiled down to static classes), it seems that feature found its way to C#. So maybe there is still hope for pattern matching and tuple support :)

Equivalent of F#'s record types would be also awesome, which is what you put as 'readonly class':

    type Person = { FirstName : string; LastName : string }
    let single = { FirstName = "Jane"; LastName = "Doe" }
    let married = { single with LastName = "Smith" }

[louthy]

Agreed on all counts . Not sure what the C# team's desire is for another classification mechanism (record types), but it could be seen as an opportunity to fix some of the problems of the past (mutable types, nullable object references).

Perhaps C#'s record type could enforce immutability on not just the record but anything it's assigned to (maybe by using 'let'). That would allow the old mutable way to co-exist with language enforced immutability. It doesn't seem like it would clutter up or modify any existing code either, so if you don't like it, you never need to see it.

Not sure how that would work when assigning to a class's member property/field. Perhaps you opt out of immutability (of the reference) with a 'mutable' keyword:

    class AClass
    {
        public mutable ARecordType Value;
    }

Functional languages also 'extend' the behaviour of a type by defining functions that work with the type. But with an object-oriented language like C# you'd still expect the functionality to come with the type I think. So I suspect it would have to look something like this:

    type Vector
    {
        float X;
        float Y;
        float Z;

        int Length => Math.Sqrt(X*X+Y*Y+Z*Z);

        Vector Add( Vector value ) => new Vector { X+value.X,Y+value.Y,Z+value.Z };
    }

So it turns the entire class into one big constructor (with everything public by default). All non-expression fields should be provided when you instantiate the object:

    let obj = new Vector { X=1, Y=2, X=3 };

I'd be very happy with that. Maybe I'll fork the compiler and have a go... if I can just find the time.... gah