Does Haskell have List Slices (i.e. Python)?

Question

Does Haskell have similar syntactic sugar to Python List Slices?

For instance in Python:

x = ['a','b','c','d'] x[1:3]  

gives the characters from index 1 to index 2 included (or to index 3 excluded):

['b','c'] 

I know Haskell has the (!!) function for specific indices, but is there an equivalent "slicing" or list range function?

Answer 1

There's no built-in function to slice a list, but you can easily write one yourself using drop and take:

slice :: Int -> Int -> [a] -> [a] slice from to xs = take (to - from + 1) (drop from xs) 

It should be pointed out that since Haskell lists are singly linked lists (while python lists are arrays), creating sublists like that will be O(to), not O(to - from) like in python (assuming of course that the whole list actually gets evaluated - otherwise Haskell's laziness takes effect).

Answer 2

If you are trying to match Python "lists" (which isn't a list, as others note) then you might want to use the Haskell vector package which does have a built in slice. Also, Vector can be evaluated in parallel, which I think is really cool.