映射应用于Haskell中的多个参数

Question

有没有办法使用Haskell的"地图"或类似的多个参数？

即找到给定点(定义为元组)与其他点列表之间的距离:

map distance (-3,-3) buildings

显然,这不起作用,因为它试图将"距离"映射到(-3,-3),其中距离需要两个元组:

let distance pointA pointB = sqrt ( (frst pointB - frst pointA) * (frst pointB - frst pointA) + (scnd pointB - scnd pointA) * (scnd pointB - scnd pointA) )

距离取两个点作为参数:在这个例子中,一个是(-3,-3),一个是从"建筑物"列表中选择的.

(-3,-3)只是一个例子.这必须是一个变量; 它不能硬编码到函数中.

也许这会更有意义:

buildings = [(3,-2),(2,1),(5,3),(4,3),(4,-1)]

firstDiff pointA pointB = subtract ( fst pointA ) ( fst pointB )

secondDiff pointA pointB = subtract ( snd pointA ) ( snd pointB )

distance pointA pointB = sqrt ( (firstDiff pointA pointB) * (firstDiff pointA pointB) +     (secondDiff pointA pointB) * (secondDiff pointA pointB))

--- What I need to happen here is a list "score" to be created by taking all distances from a point in a list lPoints to a point in list buildings.

Answer 1

allDistances src dests = map (\point -> distance src point) dests

allDistances src dests = map (distance src) dests

allDistances src = map (distance src)

allDistances = map . distance

Answer 2

你要:

map (distance (-3, -3)) buildings

是的

map f buildings 
  where f = distance (-3, -3)