kevinadi

// MongoClient -- callbacks
var assert = require('assert')
var MongoClient = require('mongodb').MongoClient
MongoClient.connect('mongodb://localhost:27017/test', function(err,db) {
  assert.equal(null,err)
  console.log('connected')
  db.collection('test').find().toArray(function(err,res) {
    assert.equal(null,err)
    console.log(res)
  })

kevinadi

splitStr :: Eq a => [a] -> [a] -> [[a]]
splitStr sub str = split' sub str [] []
    where
    split' _   []  subacc acc = reverse (reverse subacc:acc)
    split' sub str subacc acc
        | sub `isPrefixOf` str = split' sub (drop (length sub) str) [] (reverse subacc:acc)
        | otherwise            = split' sub (tail str) (head str:subacc) acc

kevinadi

wordsWhen :: (Char -> Bool) -> String -> [String]
wordsWhen p s =  case dropWhile p s of
    "" -> []
    s' -> w : wordsWhen p s''
        where (w, s'') = break p s'

kevinadi

chunks :: Int -> [a] -> [[a]]
chunks _ [] = []
chunks n xs = (fst c) : chunks n (snd c)
    where c = splitAt n xs

chunks' :: Int -> [a] -> [[a]]
chunks' n = unfoldr (\b -> if null b then Nothing else Just (splitAt n b))

chunks'' :: Int -> [a] -> [[a]]
chunks'' n = takeWhile (not.null) . unfoldr (Just . splitAt n)

kevinadi

fold' :: (b->a->b) -> b -> [a] -> b
fold' f b [] = b
fold' f b (h:t) = fold' f (f b h) t

map' :: (a->b) -> [a] -> [b]
map' f lst = fold' (\b a -> b ++ [f a]) [] lst

map'' :: (a->b) -> [a] -> [b]
map'' f [] = []
map'' f (h:t) = f h : map'' f t