<分区>
我需要从这里出发:
[(2,"a"), (1,"a"), (1,"b"), (1,"c"), (2,"dd")]
到这里:
[([1, 2], "a"), ([1], "b"), ([1], "c"), ([2], "dd")]
到目前为止我有
combineInts listTuple = someFunc (map (\(num, str) -> ([num], str)) listTuple)
其中“someFunc”是我仍然需要弄清楚并实现的部分。我相信它应该利用 foldr、map 和/或 intercalate 来实现我的目标。有什么想法吗？
最佳答案
应该这样做:
import Data.Function (on)
import Data.List (groupBy, sort, sortBy)
out = map f . groupBy ((==) `on` snd) . sortBy (compare `on` snd) $ input
where input = [(2,"a"),(1,"a"),(1,"b"),(1,"c"),(2,"dd")]
f xs@(x:_) = (sort $ map fst xs, snd x)
main = print out
关于list - Haskell:在元组列表中组合整数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32769930/