懒惰的评估实施(Lazy Evaluation implementation)

 我有一个函数fromRange ，它接受一个过滤器函数和一个时间间隔，并返回一个满足过滤器函数的区间中所有元素的集合。 
 
 我使用列表理解来实现它： 
 
fromRange   :: (Integer->Bool) -> (Integer,Integer)  -> [Integer]
fromRange f (x,y) = [i | i<-[x..y], f i]
 
 但是它需要很长的时间，所以我找到了懒惰的评估概念，但我不知道如何实现它，任何帮助？ 

I have a function fromRange which takes a filter function and an interval and returns a set with all elements in the interval that satisfy the filter function.
 
I implemented it using list comprehension:
 
fromRange   :: (Integer->Bool) -> (Integer,Integer)  -> [Integer]
fromRange f (x,y) = [i | i<-[x..y], f i]
 
but it takes very long time with big list so I found the lazy evaluation concept but I do not know how exactly to implement it, any help??

原文：https://stackoverflow.com/questions/13476336