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1·A pure functional language like Haskell might offer type hierarchies, discriminated unions, quantification, existential types, and so on, but OOP languages typically lack these things.

象Haskell那样的纯函数型语言可以提供类型层次结构、区别合并、量化、存在类型等等，但OOP语言通常缺乏这些功能。