lists?In Haskell, lists are a data structure that stores multiple items of the same type.
[1,2,3] -- A list of integers
['a', 'b', 'c'] -- a list of characters
The code below shows how to check if a list is empty.
isEmpty :: [a] -> BoolisEmpty = \myList ->case myList of[] -> True -- if the list is empty, return true_ -> False -- otherwise, return false-- call function to check if different lists are emptymain = print(isEmpty [1,2,3], isEmpty ["a"], isEmpty [])
In the code above:
isEmpty that accepts a list as an argument and returns a Bool. The placeholder a indicates that the list may be of any data type.isEmpty takes a single list as a parameter.case-of statement to check whether or not myList is an empty list.myList is empty, then the function returns True in line 4; otherwise, it returns False in line 5.isEmpty function thrice, with a different list each time. The first two calls to isEmpty involve lists that are not empty, i.e., [1,2,3] and ["a"], so it returns False for both. The final call to isEmpty uses an empty list as the parameter, so the function returns True.