Circle

public defstruct Circle <: Shape :
  center: Point
  radius: Double with: (ensure => non-negative!)

public defn Circle (x:Double, y:Double, radius:Double) :
  Circle(Point(x,y), radius)

public defn Circle (anchor:Anchor, x:Double, y:Double, radius:Double) :
  val [vt, hr] = components(anchor)
  val x* = match(hr) :
    (hr:W) : x + radius
    (hr:C) : x
    (hr:E) : x - radius
  val y* = match(vt) :
    (vt:S) : y + radius
    (vt:C) : y
    (vt:N) : y - radius
  Circle(Point(x*,y*), radius)

public defn Circle (anchor:Anchor, radius:Double) :
  Circle(anchor, 0.0, 0.0, radius)

public defn Circle (radius:Double) :
  Circle(C, 0.0, 0.0, radius)

Circle(Point(1.0, 3.0), 1.5)
Circle(1.0, 3.0, 1.5)
Circle(C, 1.0, 3.0, 1.5)
Circle(C, 5.0)
Circle(5.0)