Awesome F# - Running Total

fsharp-runningtotal.fsx

type Split = double
type Lap = { Num : int; Split : Split }
type RunnerLap = { Lap : Lap; TotalTime : double }
  
let lap1 = { Num = 1; Split = 1.23 } 
let lap2 = { Num = 2; Split = 1.13 } 
let lap3 = { Num = 3; Split = 1.03 } 
let laps = [lap1;lap2;lap3]

let runnerLapsAccumulator =  
  Seq.scan 
    (fun rl l -> { rl with Lap = l; TotalTime = rl.TotalTime + l.Split }) 
    { Lap = { Num = 0; Split = 0.0 }; TotalTime = 0.0 }

let runnerLaps = laps |> runnerLapsAccumulator
printfn "%A" runnerLaps