Flock (elm_playground.Flock)

val neighbours : 
  radius:float ->
  Steering.vehicle list ->
  Steering.vehicle ->
  Steering.vehicle list

val separation : Steering.vehicle list -> Steering.vehicle -> Steering.vec

val alignment : Steering.vehicle list -> Steering.vehicle -> Steering.vec

val cohesion : Steering.vehicle list -> Steering.vehicle -> Steering.vec

val flock : 
  ?separation:float ->
  ?alignment:float ->
  ?cohesion:float ->
  radius:float ->
  Steering.vehicle list ->
  Steering.vehicle ->
  Steering.vec