(F#) How to declare variable and function.

It was really awful that my google browser crashed when I clicking a link by opening in other tab.

I have to re-write all the words.

And now, I use Windows Live Writer, hope no crash any more, but who can guarantee?

Just at the moment after I downloaded a plug-in of windows live write, and when inserting code, Windows Live Writer even crashed.

OK, don't want to complain more, let’s begin.

First, please take a look at a simple block of code.

// Learn more about F# at http://fsharp.net

let x = 10; // Declaring a variable.
x = 11;  // Reassigned a new value to x.


let y = 13;
let z = x + y;  // Declared z = x + y.

let add x y = x + y;

printf "x + y, %i" (add x y);

Now you have some questions. What's "let" keyword? Why you reassign a value to x? Where is the declaration of function? What's the output?

Don't worry, below is my answer.

1. "let" is a very famous keyword which can help declare variable and function.

2. Reassigned a value, because there will be a warning. In fact, in F#, most of the value cannot be changed once it been assigned, and from the compiler side, it will treat this code as static property.

3. The declaration of function is "let add x y = x + y". "add" is the name of the function, x and y are the parameters. Return value? Aha, in F# the return value will always be the last code to be executed.

4. What's the output? As you learned from my No.2 answer, the output is "x + y, 23". Note, not 24.

Hope this helpful for the beginners. I also a beginner too. ^_^

(ps: don't laugh at beginner, who won't start from a beginner?)