partition.hs

-- | The 'partition' function splits a list into sublists of length n.
partition :: Int -> [a] -> [[a]]
partition n xs = unfoldr step xs
    where step :: [a] -> Maybe ([a], [a])
          step [] = Nothing
          step ys = Just (take n ys, drop n ys)

partition.js

var unfoldr = function(step, input) {
    var list = [], pair;
    while (pair = step(input)) {
        list.push(pair[0]);
        input = pair[1];
    }
    return list;
};

var take = function(n, xs) {
    return xs.slice(0,n);
};

var drop = function(n, xs) {
    return xs.slice(n);
};

// Partition a list into sublists of length n.
var partition = function(n, xs) {
    var step = function(ys) {
        return ys.length === 0
            ? null
            : [take(n, ys), drop(n, ys)];
    };
    return unfoldr(step, xs);
};

partition.py

def partition(n, list):
    """Partition a list into sublists of length n."""
    def step(acc, item):
        current = acc[-1]
        
        if len(current) == n:
            current = []
            acc.append(current)
        
        current.append(item)
        return acc
    
    return reduce(step, list, [[]])

partition.rb

# Partition a list into sublists of length n.
def partition(n, list)
  list.inject([[]]) {|acc, item|
    current = acc.last
    
    if current.length == n
      current = []
      acc << current
    end
    
    current << item
    acc
  }
end