如何在交互式窗口中使用af＃函数？

Question

How can I execute F# function in the interactive window?

If I create a .fsx file and type following code:

open System

let parseTitle (line : string) =
    let startIndex = line.LastIndexOf('(')+1
    let endIndex = line.LastIndexOf(')')
    line.Substring(startIndex,endIndex-startIndex-1)

let testTitle = "The Possessed (The Devils) (Fyodor Dostoyevsky)"

parseTitle testTitle

Then select it all and press Alt+Enter. Nothing happens. When I set the cursor to the last line and press Alt+Enter I get following error:

error FS0039: The value or constructor 'parseTitle' is not defined

What am I doing wrong?

Answer 1

To use code from some given file, you only need to highlight it, right click, and then select "Send To Interactive". This will send the entire selection to the interactive window, as opposed to just one line. Enigmativity's answer is incorrect, as you don't need to modify your file in order to send a snippet to the interactive window. What he was referring to was this: if you type some code by hand in the interactive window, you need to end your statements with a double semi-colon ;;.

Answer 2

You need to key ;; at the end of each line (or block) to execute the code.

open System;;

let parseTitle (line : string) =
    let startIndex = line.LastIndexOf('(')+1
    let endIndex = line.LastIndexOf(')')
    line.Substring(startIndex,endIndex-startIndex-1);;

let testTitle = "The Possessed (The Devils) (Fyodor Dostoyevsky)";;

parseTitle testTitle;;

I then get:

> 
val parseTitle : string -> string

> 
val testTitle : string = "The Possessed (The Devils) (Fyodor Dostoyevsky)"

>
val it : string = "Fyodor Dostoyevsk"
>