将高阶函数从 Python 转换为 Haskell
我有以下代码：
import operator
def stagger(l, w):
if len(l)>=w:
return [tuple(l[0:w])]+stagger(l[1:], w)
return []
def pleat(f, l, w=2):
return map(lambda p: f(*p), stagger(l, w))
if __name__=="__main__":
print pleat(operator.add, range(10))
print pleat(lambda x, y, z: x*y/z, range(3, 13), 3)
print pleat(lambda x: "~%s~"%(x), range(10), 1)
print pleat(lambda a, b, x, y: a+b==x+y, [3, 2, 4, 1, 5, 0, 9, 9, 0], 4)
重要部分：Pleat 接受任何函数和任何序列，并将该序列中的前几个元素作为参数传递到接收到的函数中。
有没有办法在 Haskell 中做到这一点还是我在做梦？
I have the following code:
import operator
def stagger(l, w):
if len(l)>=w:
return [tuple(l[0:w])]+stagger(l[1:], w)
return []
def pleat(f, l, w=2):
return map(lambda p: f(*p), stagger(l, w))
if __name__=="__main__":
print pleat(operator.add, range(10))
print pleat(lambda x, y, z: x*y/z, range(3, 13), 3)
print pleat(lambda x: "~%s~"%(x), range(10), 1)
print pleat(lambda a, b, x, y: a+b==x+y, [3, 2, 4, 1, 5, 0, 9, 9, 0], 4)
Important part: Pleat takes any function and any sequence and passes the first handful of elements from that sequence into the received function as parameters.
Is there a way to do this in Haskell or am I dreaming?
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下面的类型签名是可选的：
stagger :: [a] -> Int -> [[a]] stagger l w | length l >= w = take w l : stagger (tail l) w | otherwise = [] pleat :: ([a] -> b) -> [a] -> Int -> [b] pleat f l w = map f $ stagger l w main = do print $ pleat (\[x, y] -> x+y) [0..9] 2 print $ pleat (\[x, y, z] -> x*y/z) [3..12] 3 print $ pleat (\[x] -> "~" ++ show x ++ "~") [0..9] 1 print $ pleat (\[a, b, x, y] -> a+b == x+y) [3, 2, 4, 1, 5, 0, 9, 9, 0] 4这个想法是该函数明确将未知长度的列表作为参数，因此它不是非常类型安全的。但它几乎是 Python 代码的一对一映射。
The type signatures below are optional:
stagger :: [a] -> Int -> [[a]] stagger l w | length l >= w = take w l : stagger (tail l) w | otherwise = [] pleat :: ([a] -> b) -> [a] -> Int -> [b] pleat f l w = map f $ stagger l w main = do print $ pleat (\[x, y] -> x+y) [0..9] 2 print $ pleat (\[x, y, z] -> x*y/z) [3..12] 3 print $ pleat (\[x] -> "~" ++ show x ++ "~") [0..9] 1 print $ pleat (\[a, b, x, y] -> a+b == x+y) [3, 2, 4, 1, 5, 0, 9, 9, 0] 4The idea is that the function is explicit about taking a list of unknown length as an argument, so it is not very type-safe. But it is pretty much a 1-to-1 mapping of the Python code.