anchor.diff:      /// A basic particle.
       type [<NoEquality; NoComparison; Struct>] BasicParticle =
           { mutable Life : Life
  -          Bod : Body
  -          Siz : Vector2
  -          Off : Vector2
  -          Ins : Vector4
  -          Col : Color
  -          Glo : Color
  -          Flp : Flip }
  +          mutable Body : Body
  +          mutable Size : Vector2
  +          mutable Offset : Vector2
  +          mutable Inset : Vector4
  +          mutable Color : Color
  +          mutable Glow : Color
  +          mutable Flip : Flip }
           interface Particle with member this.Life with get () = this.Life and set value = this.Life <- value
  -        static member inline bod = Scope.make (fun pex -> pex.Bod) (fun bod pex -> { pex with Bod = bod })
  -        static member inline col = Scope.make (fun pex -> pex.Col) (fun col pex -> { pex with Col = col })
  -        static member inline ins = Scope.make (fun pex -> pex.Ins) (fun ins pex -> { pex with Ins = ins })
  +        static member inline body = Scope.make (fun p -> p.Body) (fun v p -> { p with Body = v })
   
       /// A basic particle emitter.
       type BasicEmitter = Emitter<BasicParticle>
positive.code: 
      /// Describes the body of an instance value.
      type [<NoEquality; NoComparison; Struct>] Body =
          { Position : Vector2
            Rotation : single
            LinearVelocity : single
            AngularVelocity : single
            Gravity : Vector2 }
  
      /// The base particle type.
      type Particle =
  
negative.code:                 let emitCount = int emitCountThisFrame - int emitCountLastFrame
                  for _ in 0 .. dec emitCount do Emitter<'a>.emit time constrain emitter
  
              // update existing particles in-place
              let outputInPlace = emitter.InPlaceBehavior time constrain emitter
  
              // update existing particles compositionally
              let (particles, outputCompositional) = CompositionalBehaviors.run time emitter.CompositionalBehaviors emitter.Particles
              let emitter = { emitter with Particles = particles }
  
              // compose output
              let output = outputCompositional + outputInPlace
              (emitter, output)
  
          interface Emitter with
  