对列表的所有元素应用 function 并根据函数的返回类型返回一个新列表

Question

I want to apply a lambda function through a map on a list of vectors and be able to get a list of Booleans from the results and then compare all elements in the list of Booleans

lambda = (\ list x -> distance (x (5,5)) < 10) 

[(0,1),(1,6),(15,36)] -> 

Apply the lambda on each elements, which would give: [True, True, False] and then check if all elements are True

I tried to do this

checkConvergence :: [Vector] -> Vector -> Bool
checkConvergence list y = map (\ list x -> distance (x y) < 10)  list

But I got this:

 Couldn't match expected type 'Bool' with actual type [(Vector -> Vector) -> Bool]

Answer 1

Three problems:

1. You want \ x -> instead of \ list x -> .
2. map will give you a list of Bool s. If you want to know if they're all true, then you need to either use all instead, or wrap the result in and .
3. Unless Vector is an alias for some weird function type, you probably meant distance xy or distance (x,y) instead of distance (xy) .