RosettaCodeData/Task/Polymorphism/E/polymorphism-1.e

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def makePoint(x, y) {
def point implements pbc {
to __printOn(out) { out.print(`<point $x,$y>`) }
to __optUncall() { return [makePoint, "run", [x, y]] }
to x() { return x }
to y() { return y }
to withX(new) { return makePoint(new, y) }
to withY(new) { return makePoint(x, new) }
}
return point
}
def makeCircle(x, y, r) {
def circle extends makePoint(x, y) implements pbc {
to __printOn(out) { out.print(`<circle $x,$y r $r>`) }
to __optUncall() { return [makeCircle, "run", [x, y, r]] }
to r() { return r }
to withX(new) { return makeCircle(new, y, r) }
to withY(new) { return makeCircle(x, new, r) }
to withR(new) { return makeCircle(x, y, new) }
}
return circle
}