不在haskell中编译printf

Question

伙计们请告诉我为什么这不是编译

putStrLn("The average number of fans for the films of " ++ actor ++ " is : " ++ printf "%.2f\n" (show(countAveFans actor testDatabase))

它很简单但我不能想为什么它不起作用.我尝试将整个事物转换为字符串并取出2小数点打印出来.谢谢

Answer 1

你需要提供一个RealFloat而不是一个String来printf删除调用show:

putStrLn $ "The average number of fans for the films of " ++ actor ++ " is : " ++ (printf "%.2f\n" $ countAveFans actor testDatabase)