如何优雅地实现 blowup 函数呢？

Question

blowup 函数的定义如下：

“abc” ->"abbccc"
"abcd" -> "abbcccdddd"
....

我写了个实现，但是觉得不太优雅，有没有更直接更优雅一些的写法呢？

blowup :: String -> String blowup [] = [] blowup xs = concat [take (fst x) (repeat (snd x)) | x <- zip [1..] xs]

Answer 1

与一楼的类似

2. blowup xs = concat [take n (repeat c) | (c, n) <- zip xs [1..]]

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Answer 2

我也来一个

2. f (x:xs)= (return x) : (zipWith (:) xs (f xs))

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Answer 3

flw 兄一出手，果然，佩服，学习ing.

Answer 4

blowup = concat . zipWith replicate [1..]

Answer 5

或者下面这个实现？

blowup2 :: String -> String blowup2 [] = [] blowup2 xs = (blowup2 . init) xs ++ take (length xs)  (repeat  (last xs) )