Retrieving a list of values ​​from a list of maybes without ofJust

Question

Input: [Just "foo", Just "bar", Nothing, Just "quux"]

Output: ["foo", "bar", "quux"]

I am not satisfied with the following solution using fromJust , because it is not very portable for elm, which does not like unsafe functions:

extract list = map fromJust $ filter isJust list

Is there another concise / idiomatic way to achieve this?

Answer 1

You can use catMaybes :

 import Data.Maybe catMaybes list 

Answer 2

 Λ: :m + Data.Maybe Λ: concatMap maybeToList [Just "foo", Just "bar", Nothing, Just "quux"] ["foo","bar","quux"]