Explaining parts of F#

tryfsharp.fs

let mergeStrings a b c = // string -> (string -> (string -> string))
  a + b + c
let test = mergeStrings "foo" "bar"
printfn "%A" (test "kalle")
printfn "%A" ("foo", 2)
//[<CLIMutable>]
type Dep = {
    getIt : string -> string
    kind : string
}
with
  member this.getKind = this.kind
type Dep
with
  member this.getConstant = 3
let doWork (d: Dep) param : string =
  d.getConstant |> printfn "herro %d"
  printfn "%A" d
  d.getIt param
let work =
  doWork {
     getIt = fun x -> "I am dep. You are: " + x
     kind = "hardcoded" } 
work "teh win"
|> (printfn "work result: %s")