I'm trying to figure out C#'s syntax for anonymous functions, and something isn't making sense to me. Why is this valid
Func<string, string> f = x => { return "Hello, world!"; };
but this isn't?
Func<string> g = { return "Hello, world!"; };
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2 Answers
The second still requires the lambda syntax:
Func<string> g = () => { return "Hello, world!"; };
In the first, you're effectively writing:
Func<string, string> f = (x) => { return "Hello, world!"; };
But C# will let you leave off the () when defining a lambda if there is only a single argument, letting you write x => instead. When there are no arguments, you must include the ().
This is specified in section 7.15 of the C# language specification:
In an anonymous function with a single, implicitly typed parameter, the parentheses may be omitted from the parameter list. In other words, an anonymous function of the form
( param ) => expr
can be abbreviated to
param => expr
Comments
You need to know the function definition:
Encapsulates a method that has one parameter and returns a value of the type specified by the TResult parameter.
References:
1 Comment
Servy
Func<string> (which is what his second example is using) is a function that takes no parameters and returns a string.