The Haskell type signatures are take :: Int -> [a] -> [a] and drop :: Int -> [a] -> [a]. These definitions also handle nonpositive counts as the Prelude does:
take n _ | n <= 0 = []
take _ [] = []
take n (x:xs) = x : take (n-1) xs

drop n xs | n <= 0 = xs
drop _ [] = []
drop n (_:xs) = drop (n-1) xs
The wildcard in the first equation matters under lazy evaluation: take 0 undefined yields [] without inspecting its list argument. The remainder of this question uses nonnegative counts.[ref]

Ancestors (12)

  1. a
  2. 1
  3. Functional programming, design and analysis of algorithms (resit)
  4. 2016
  5. Past exam of the year 1 of the computer science course of the University of Oxford
  6. Year 1 of the computer science course of the University of Oxford
  7. Computer science course of the University of Oxford
  8. Undergraduate course of the University of Oxford
  9. Course of the University of Oxford
  10. University of Oxford
  11. List of universities
  12. Home

View article source

Discussion (0) New discussion

There are no discussions about this article yet.

Articles by others on the same topic (0)

There are currently no matching articles.
See all articles in the same topic Create my own version