[英]Using all with multi argument function
Let's say I have a function a that takes one argument, and a list b with possible inputs, defined as: 假设我有一个带有一个参数的函数a和一个带有可能输入的列表b,定义如下:
let a x1 = x1 == 3
let b = [3, 3]
Now I want to test that all values in b returns True as arguments to a, which I can do with the all function: 现在我想测试b中的所有值都返回True作为a的参数,我可以使用all函数:
all a b
> True
However, can I do something similar if a would take two arguments and b would be a list of tuples where each value in the tuple correspond to each argument? 但是,如果a将采用两个参数并且b将是元组列表,其中元组中的每个值对应于每个参数,我可以执行类似的操作吗?
Eg: 例如:
let a x1 x2 = x1 == 3 && x2 == 1
let b = [(3,1), (3,1)]
all a b
This returns: 返回:
<interactive>:1:4:
Couldn't match expected type `Bool'
against inferred type `a1 -> Bool'
In the first argument of `all', namely `a'
In the expression: all a b
In the definition of `it': it = all a b
Any ideas on how to do this? 关于如何做到这一点的任何想法?
To turn a function with two arguments into a function expecting one pair, use 要将具有两个参数的函数转换为期望一对的函数,请使用
uncurry :: (r -> s -> t) -> (r, s) -> t
So, how about 那么,怎么样
all (uncurry a) b
? ?
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