lists?In Haskell, lists are a data structure that store multiple items of the same type.
[1,2,3] -- A list of integers
['a', 'b', 'c'] -- a list of characters
lists in HaskellWe can merge two lists through the ++ operator. The code below demonstrates the process:
merge :: [a] -> [a] -> [a]merge = \s1 -> \s2 ->case s1 of[] -> s2 -- If list1 is nil, return list2_ -> -- otherwisecase s2 of[] -> s1 -- if list2 is nil, return list1_ -> s1 ++ s2 -- otherwise merge lists using (++) operator-- call function to merge listsmain = print(merge [1,2,3] [4,5,6])
In the code above:
merge that accepts two lists as arguments and also returns a list. The placeholder a indicates that the lists may be of any data type, but the data types of both lists must be the same.merge takes two lists called s1 and s2 as parameters.case-of statement to check if s1 is an empty list. If s1 is empty, then merge returns s2 in line 4.s1 is not empty, then the function checks if s2 is empty in line 7. If s2 is empty, then the function returns s1.lists are not empty, then the ++ operator is used to merge them in line 8.merge function and print the returned list.