An F# FP example

FunctionalPoints.fs

open System

type Point = { x : double; y : double }

let distance (start : Point) (finish : Point) : double =
    let x = finish.x - start.x
    let y = finish.y - start.y
    sqrt (x * x + y * y)

[<EntryPoint>]
let main argv = 
    let p1 = { x = 0.0; y = 0.0 }
    let p2 = { x = 3.0; y = 4.0 }

    distance p1 p2 |> printfn "%f"

    printfn ""

    let points = [
        { x = 0.0; y = 4.0 };
        { x = 3.0; y = 4.0 };
        { x = 5.0; y = 12.0 }
    ]

    let origin = { x = 0.0; y = 0.0 }
    let distancesFromOrigin = points |> Seq.map (distance origin)

    for d in distancesFromOrigin do
        printfn "%f" d

    0