Menu
okay, this is probably going to be in the prelude, but: is there a standard library function for finding the unique elements in a list? my (re)implementation, for clarification, is:
has :: (Eq a) => [a] -> a -> Bool has [] _ = False has (x:xs) a | x == a = True | otherwise = has xs a unique :: (Eq a) => [a] -> [a] unique [] = [] unique (x:xs) | has xs x = unique xs | otherwise = x : unique xs 
912
if it is just about knowing if the list contains duplicates you can use the nub function in Data. List like so: hasDup l = nub l == l (nub removes all duplicates... so this will be true only if there are no duplicates in the list.)
Haskell also incorporates polymorphic types---types that are universally quantified in some way over all types. Polymorphic type expressions essentially describe families of types. For example, (forall a)[a] is the family of types consisting of, for every type a, the type of lists of a.
I searched for (Eq a) => [a] -> [a] on Hoogle.
First result was nub (remove duplicate elements from a list).
Hoogle is awesome.
117
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
