F# Functions

In Visual Studio Code enter the following code then, to run it, highlight it and press Option Enter:

let helloWorld = 
    "Hello from FSI"

printfn "%s" helloWorld

and get this result:

Hello from FSI

In Visual Studio Code enter the following code then, to run it, highlight it and press Option Enter:

let prefix preStr postStr = 
  preStr + ", " + postStr

prefix "Hello" "Greg"

and get this result:

val it : string = "Hello, Greg"

In Visual Studio Code enter the following code then, to run it, highlight it and press Option Enter:

let names = ["Joe"; "Sue"; "Mary"; "Bill"]

names
|> Seq.map (prefix "Hello")

and get this result:

val it : seq =
  seq ["Hello, Joe"; "Hello, Sue"; "Hello, Mary"; "Hello, Bill"]