du.js

function constant(value) {
    return function() {
        return value
    }
}

function compose(fun1, fun2) {
    if(arguments.length === 2) {
        return function(/*args*/) {
            return fun1(fun2.apply(null, arguments))
        }
    } else {
        var functions = Array.prototype.slice.call(arguments)
        var len = functions.length
        return function(/*args*/) {
            var value = (functions[len - 1]).apply(null, arguments)
            var i
            for(i = Math.max(0, len - 2); i >= 0; i--) {
                value = (functions[i]).call(null, value)
            }
            return value
        }
    }
}

function property(key) {
    return function(thing) {
        return thing[key]
    }
}

function key(obj) {
    return obj.key
}

function value(obj) {
    return obj.value
}

function window2(a) {
    return a.map(function(value, index, array) {
        return [value, array[index + 1]]
    }).slice(0, a.length - 1)
}

function bind0(rootSelection, cssClass, element, dataFlow) {
    element = element || 'g' // fixme switch from variadic to curried
    dataFlow = typeof dataFlow === 'function' ? dataFlow
        : (dataFlow === void(0) ? function(d) {return [d]} : constant(dataFlow))
    var binding = rootSelection.selectAll('.' + cssClass).data(dataFlow, key)

    binding.entered = binding.enter().append(element)
    binding.entered.classed(cssClass, true)

    return binding
}

function bind(object, key) {
    var result = bind0.apply(null, arguments)
    object[key] = result
    return result
}

function translate(funX, funY) {
    return function(d, i) {
        return 'translate(' + (typeof funX === 'function' ? funX(d, i) : funX) + ','
            + (typeof funY === 'function' ? funY(d, i) : funY) + ')'
    }
}

function translateX(funX) {
    return function(d, i) {
        return 'translate(' + (typeof funX === 'function' ? funX(d, i) : funX) + ', 0)'
    }
}

function translateY(funY) {
    return function(d, i) {
        return 'translate(0, ' + (typeof funY === 'function' ? funY(d, i) : funY) + ')'
    }
}