weird-adder.hs

-- weird-adder.hs - Josh Sandlin - 6:45PM - 2/14/2010
-- wierd-adder.hs - Tenor Biel - 12:09PM - 2/13/201
-- Really weird way to add a range of numbers

-- takes an upper limit and returns a list of pairs
pairedRange :: Int -> [(Int, Int)]
pairedRange x = zip (filter odd [1..x]) (filter even [1..x])

-- adds a list of pairs
addPairs :: Num a => [(a, a)] -> [a]
addPairs = map (uncurry (+))

-- takes a number, builds a range, adds the pairs, then sums the list
sumPairedRange :: Int -> Int
sumPairedRange = sum . addPairs . pairedRange

sum' :: Int -> Int
sum' = sumPairedRange

-- sum [1..20] => 210
-- sum' 20     => 210 <- 20 is the upper limit of the range

Interesting. I didn't know about the dot notation back when I was messing with this.