Lambda expression vs anonymous methods

Question

I would like to know what is the difference. Currently I am learning this stuff and it seems to me like these are just the same:

delegate void X();

X instanceOfX;

instanceOfX = delegate() { code };

instanceOfX = () => { code };

Also if the lambda are newer, should I just use lambda and forget on anonymous methods?

Solution 1

Yes, lambda expressions are just very special anonymous methods.

However, there are some deep differences. Start with Eric Lippert's Lambda Expression vs. Anonymous Methods, Part One and continue to the rest of the series.

Solution 2

The only difference is the lambda can be easily cast to Expression<Func<void>>. The delegates are purely just methods/closures, but the lambda can also be broken down into an expression tree:

Expression<Func<int, int>> expr = x => x*2; // Expression tree
Func<int, int> fun = x => x*2;              // Function
delegate int MyDelegate(int x);             // Delegate
MyDelegate del = x => x*2;                  // Same as Function and Delegate

Comments

[Anthony Pegram]

Think in terms of evolution of the language. In C# 1, we had delegates. In C# 2, they added anonymous methods. C# 3 added lambdas. Easier ways to accomplish similar tasks. For more on the evolution, I would encourage you to check out the book C# In Depth.

[B Bulfin]

So what's special about them?

[lojol]

What is special about them<? thanks

[Doctor Jones]

@recursive for a start, one MAJOR difference is that single line Lambdas can be assigned to an Expression tree whereas Anonymous methods cannot.

[CodesInChaos]

Note that this is only possible for a subset of lamdas: Expression-lamdas but not statement lamdas.

[Eric Lippert]

Note that "Delegate" is a terrible name for a delegate type because it will be easily confused with System.Delegate, its base class.

[kelloti]

I apologize. I'm still drinking coffee this morning and I honestly couldn't think of another name

[BlaShadow]

I prefer anonymous method, I'm not always using linq otherwise I like use FindAll from List.