zakaluka

let day1part1 = partOne "R2, L5, L4, L5, R4, R1, L4, R5, R3, R1, L1, L1, R4, L4, L1, R4, L4, R4, L3, R5, R4, R1, R3, L1, L1, R1, L2, R5, L4, L3, R1, L2, L2, R192, L3, R5, R48, R5, L2, R76, R4, R2, R1, L1, L5, L1, R185, L5, L1, R5, L4, R1, R3, L4, L3, R1, L5, R4, L4, R4, R5, L3, L1, L2, L4, L3, L4, R2, R2, L3, L5, R2, R5, L1, R1, L3, L5, L3, R4, L4, R3, L1, R5, L3, R2, R4, R2, L1, R3, L1, L3, L5, R4, R5, R2, R2, L5, L3, L1, L1, L5, L2, L3, R3, R3, L3, L4, L5, R2, L1, R1, R3, R4, L2, R1, L1, R3, R3, L4, L2, R5, R5, L1, R4, L5, L5, R1, L5, R4, R2, L1, L4, R1, L1, L1, L5, R3, R4, L2, R1, R2, R1, R1, R3, L5, R1, R4"

zakaluka

let distance stloc endloc = (abs (stloc.x - endloc.x)) + (abs (stloc.y - endloc.y))

let partOne strList = 
  strList |> moveAll |> fun x -> distance startPt x.pt

zakaluka

let moveAll strList = 
  Regex.Matches (strList, @"[LR]\d+")
  |> Seq.cast
  |> Seq.fold 
    (fun oldloc (instr : System.Text.RegularExpressions.Match) -> 
      move 
        (instr.Value.[0] |> toTurn) 
        (instr.Value.Substring 1 |> int)
        oldloc
    )

zakaluka

let move way dist = (turn way) >> (advance dist)

zakaluka

let advance dist loc = 
  match loc.dir with
  | North -> 
    let npt = { x = loc.pt.x; y = loc.pt.y + dist }
    { loc with pt = npt }
  | South -> 
    let npt = { x = loc.pt.x; y = loc.pt.y - dist }
    { loc with pt = npt }
  | West -> 
    let npt = { x = loc.pt.x - dist; y = loc.pt.y }

zakaluka

let turn way loc = 
  match way with
  | L -> 
    match loc.dir with
    | North -> { loc with dir = West }
    | West -> { loc with dir = South }
    | South -> { loc with dir = East }
    | East -> { loc with dir = North }
  | R ->
    match loc.dir with

zakaluka

let toTurn = function 
  | 'R' -> R
  | 'L' -> L
  | _ -> failwith "Unknown turn type"

zakaluka

let startPt = {
  x = 0
  y = 0
}

let startLoc = {
  dir = North
  pt = startPt
}

zakaluka

type Direction = 
  | North 
  | South 
  | East 
  | West

type TurnTo = 
  | R
  | L

zakaluka

let advance dist loc = 
  match loc.dir with
  | North -> 
    let npt = { x = loc.pt.x; y = loc.pt.y + dist }
    { loc with pt = npt }
  | South -> 
    let npt = { x = loc.pt.x; y = loc.pt.y - dist }
    { loc with pt = npt }
  | West -> 
    let npt = { x = loc.pt.x - dist; y = loc.pt.y }