Question

I need to be able to write a function that shows repeated words from a string and return a list of strings in order of its occurrence and ignore non-letters

e.g at hugs prompt

repetitions :: String -> [String]  repetitions > 'My bag is is action packed packed.' output> ['is','packed'] repetitions > 'My name  name name is Sean .' output> ['name','name'] repetitions > 'Ade is into into technical drawing drawing .' output> ['into','drawing'] 

Answer 1

To split a string into words, use the words function (in the Prelude). To eliminate non-word characters, filter with Data.Char.isAlphaNum. Zip the list together with its tail to get adjacent pairs (x, y). Fold the list, consing a new list that contains all x where x == y.

Someting like:

repetitions s = map fst . filter (uncurry (==)) . zip l $ tail l   where l = map (filter isAlphaNum) (words s) 

I’m not sure that works, but it should give you a rough idea.