如何比较列表中的两个元组？

Question

我有这样的元组列表：

[(0.0,0.0),(1.0,0.0),(2.0,0.0),(3.0,0.0),(3.0,0.0),(3.0,0.0),(4.0,0.0),(4.0,0.0)]

其中第一个元素是X坐标，第二个元素是Y坐标，我现在想编写将返回的函数：

[(0.0,0.0),(1.0,0.0),(2.0,0.0),(3.0,0.0),(3.0,1.0),(3.0,2.0),(4.0,0.0),(4.0,1.0)]

它从第一个元组中取出第一个元素，从第二个元组中取出第一个元素，如果它们不相等，则Y不变，但如果它们相等，则将Y加一个。

如果有人有想法如何在Haskell中写作？

Answer 1

尚未测试，但可以执行以下操作：

foo :: [(Float, Float)] -> [(Float, Float)]
foo []  = []
foo [x] = [x]
foo ((xx, xy):(yx, yy):xs) = (xx, xy): theTuple : (foo ((yx, yy):xs))
    where
        theTuple = if xx == yx then (yx, yy) else (yx, yy+1)