How do I use recursion with lists in Haskell?

How do I use recursion with lists in Haskell?

In Haskell, recursion is a common way to process lists. You define a function that calls itself with a smaller part of the list.

Can you give me an example of a recursive function that sums a list?

Sure! Here's a simple recursive function to sum a list:

sumList :: Num a => [a] -> a
sumList [] = 0
sumList (x:xs) = x + sumList xs

What does the pattern x:xs mean in that function?

The pattern x:xs is a way to deconstruct a list. x is the head (first element), and xs is the tail (the rest of the list).

Are there any base cases I should be aware of when using recursion?

Yes, every recursive function should have a base case to prevent infinite recursion. In the sum example, the base case is when the list is empty ([]).