转换数字基数

Question

是否有平台功能可以执行以下操作？

convertBase :: (Num a, Num b) => Int -> Int -> [a] -> [b]

将数字从基数'a'转换为基数'b',其中每个列表项是数字中的数字.例如:

convertBase 2 10 [1,1,0,1] = [1, 3]

我希望这是有道理的,如果我能清除任何事情,请告诉我

Answer 1

使用Hackage中的数字包:

import Data.Digits (digits, unDigits)

convertBase :: Integral a => a -> a -> [a] -> [a]
convertBase from to = digits to . unDigits from

fromIntegral如果需要输入和输出类型不同,可以在其中添加.此外,Integral约束更有意义Num,因为您可能不想处理复杂或浮点数字.

Answer 2

haskell平台中最接近的是模块Numeric:

readInt :: Num a => a -> (Char -> Bool) -> (Char -> Int) -> ReadS a
showIntAtBase :: Integral a => a -> (Int -> Char) -> a -> ShowS

fromBase :: Int -> String -> Int
fromBase base = fst . head . readInt base ((<base).digitToInt) digitToInt

toBase :: Int -> Int -> String
toBase base num = showIntAtBase base intToDigit num ""

fromBaseToBase :: Int -> Int -> String -> String
fromBaseToBase from to = toBase to . fromBase from