How to filter my list of tuples of two input lists?

Question

I am trying to generate all possibles combinations from two lists and then only return those that match the lambda function. So I currently have the following code:

func :: [a] -> [b] -> ((a, b) -> Bool) -> [(a, b)]
func xs ys f = filter f (tup)
    where
        tup = concat(map (\x -> map (\y -> (x,y))ys) xs)

Currently I am able to generate all the possible combinations, but the filtering won't work.

Error for the input : func [1,2,3] [4,5] (\ a b -> a+b > 6)

• Couldn't match expected type ‘Bool’ with actual type ‘(a, b) -> Bool’

• The lambda expression ‘\ a b -> a + b > 7’ has two value arguments, but its type ‘(a, b) -> Bool’ has only one

How can I solve this?

I tried to use map instead of filter, but that did not work as well.

You almost got it, try func [1, 2, 3] [4, 5] (\(a, b) -> a+b > 6) instead. — Micha Wiedenmann
– Micha Wiedenmann, Commented Nov 24, 2022 at 14:36

Daniel Wagner · Accepted Answer · 2022-11-24 15:14:56Z

4

Making a function with two arguments and making a function with a single 2-tuple argument use slightly different syntax:

\a b -> a+b > 6 -- two arguments
\(a, b) -> a+b > 6 -- one tuple argument

answered Nov 24, 2022 at 15:14

Daniel Wagner

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