在Haskell中在元组中打印值 [英] Printing the values inside a tuple in Haskell

问题描述

我有一个元组列表.例如: [("A"，100,1)，("B"，101,2)] .我需要以一种简单的方式来显示它.例如:您的名字是:A"，您的id是:100" .

I have a list of tuples. For example: [("A",100,1),("B",101,2)]. I need to display it in a simple way. For example: "your name is: A", "Your id is: 100".

如果任何人都可以找到解决方案，那将是一个很大的帮助.预先感谢.

If anyone can find a solution for this, it would be a great help. Thanks in advance.

推荐答案

最简单的方法是创建一个适用于列表中元素之一的函数.因此，您将需要以下内容:

The easiest way to do this is to create a function that works for one of the elements in your list. So you'll need something like:

showDetails :: (String, Int, Int) -> String
showDetails (name, uid, _) = "Your name is:" ++ name ++ " Your ID is: " ++ show uid

然后您将此功能应用于列表中的每个元素，这意味着您要使用映射功能:

Then you would apply this function to each element in the list, which means you want to use the mapping function:

map :: (a -> b) -> [a] -> [b]

因此，如果您的列表名为 xs ，则可能需要以下内容:

So, if your list is called xs, you would want something like:

map showDetails xs

这显然为您提供了 [String] 类型的结果，因此您可能对 unlines 函数感兴趣:

This obviously gives you a result of type [String], so you might be interested in the unlines function:

unlines :: [String] -> String

这只是获取一个字符串列表，并创建一个字符串，每个元素之间都用新行分隔.

This simply takes a list of strings, and creates a string where each element is separated by a new line.

将所有内容放在一起，即可为您提供:

Putting this all together, then, gives you:

main :: IO ()
main = putStrLn . unlines . map showDetails $ [("A",100,1),("B",101,2)]

这篇关于在Haskell中在元组中打印值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！