Discussion on: Write a script to identify an anagram

[Heiko Dudzus]

I like the solution to "subtract" all characters of the shorter word from the (possibly) longer word, and check if there is some character left:

import Data.List(delete,sortBy)
import Data.Function(on)

-- deletes the first character of word from str
del str word = delete (head word) str

-- deletes all chars of word from str
str `without` word = foldl del str (map (:[]) word)

-- are there any remaining characters? 
isAnagram word1 word2 = null $ longer `without` shorter
  where [shorter,longer] = sortBy (compare `on` length) [word1,word2]

Ok, this is more fun, but it somehow reimplemented the library function ( \ \ ) (which can be read as the difference operation in set theory)

import Data.List((\\),sortBy)
import Data.Function(on)
isAnagram word1 word2 = null $ longer \\ shorter
  where [shorter,longer] = sortBy (compare `on` length) [word1,word2]

[Heiko Dudzus]

I'm sorry, it took me a dinner out to see, this was unnecessarily complicated. :) The delete functions perfectly fits a right fold. And if the words aren't of equal length, they are not anagrams.

-- deletes the first occurance of element x from a list
delete _ [] = []
delete x (y:ys) = if x == y then ys else y : delete x ys

-- deletes all elements of the second list from the first
without :: Eq a => [a] -> [a] -> [a]
without = foldr delete

-- are there any remaining characters? 
isAnagram word1 word2 = null $ word1 `without` word2

delete could also be imported from Data.List