如何构建Haskell＆＃x27;＃＆＃x27;山？
定义了一种称为山的功能，该功能吸引了一个高度n和宽度，可以从东部（右）攀登。每行将山从上到下扩大一个字符。这座山应该由“＃”角色组成，山的不同层次被Newline角色隔开。在山尽头没有新的line角色。高度为负的山的高度应等于0，因此在这种情况下，结果应为空列表。
您是否知道我在其他情况下可以写什么？
mountain :: Int -> String
mountain a
| a < 1 = ""
| a == 1 = "#"
| a == 2 == "#\n##"
| otherwise = ???
Define a function called mountain that draws a mountain of height n and width that can be climbed from the east (right). Widen the mountain from top to bottom by one character per line. The mountain should consist of '#' characters, with the different levels of the mountain separated by the newline character. No more new line characters at the end of the mountain. A mountain with a negative height should be equal to a height of 0, so in this case the result should be an empty list.
Do you have any idea what I could write in the otherwise case ?
mountain :: Int -> String
mountain a
| a < 1 = ""
| a == 1 = "#"
| a == 2 == "#\n##"
| otherwise = ???
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您可以使用累加器：一个包含
＃字符的数量的变量，然后对这些项目进行递归调用。然后，
Mountain功能看起来像：您需要填写
…零件。一种更优雅的方法可能是使用
map在其中我们从1到n 创建列表，以及该行的字符串上的每个时间映射，然后使用字符串] - ＆gt;字符串 将这些字符串加在一起：You can work with an accumulator: a variable that contains the number of
#characters you need to write, and then makes a recursive call for these items.The
mountainfunction then looks like:where you need to fill in the
…parts.A more elegant approach might be to use
mapwhere we create a list from1ton, and each time map on a string for that line, and then useunlines :: [String] -> Stringto join these strings together: