21 lines
254 B
Scala
21 lines
254 B
Scala
scala> val h = new HVar(3)
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h: HVar[Int] = HVar(3)
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scala> h := 11
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scala> h := 90
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scala> !h
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res32: Int = 90
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scala> h.history
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res33: List[Int] = List(90, 11, 3)
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scala> h.undo
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res34: Int = 90
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scala> h.undo
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res35: Int = 11
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scala> h.undo
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res36: Int = 3
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