How to reimplement the "all" function in Haskell?

Question

I need to define a functionall' :: ( a -> Bool ) -> [a] -> Bool which verifies if all the elements from a list satisfy a certain condition .

For example : all' ( <5) [1,2,3] = True , all' (>=2) [1,1,2,2,3,3] = False.

My main problem is that I don't know how to handle the transmission of a function.

Answer 1

Functions in Haskell are passed just like any other value. Here's an example to help you progress:

doBothSatisfy :: (a -> Bool) -> a -> a -> Bool
doBothSatisfy p x y = (p x) && (p y)

And now the usage:

doBothSatisfy (> 5) 6 7 == True
doBothSatisfy (> 5) 1 8 == False

Now try to extend that to lists.