Restructures items using given `f`.

restructure.js

function restructure(input, f, start) {
  return reducible(function(next, initial) {
    var state = start
    return reduce(input, function(item, result) {
      var change = [].concat(f(item, state))
      state = change[0]
      var value = change[1]
      
      return value ? next(value, result) :
             result
    }, initial)
  })
}

var coreduction = require("coreduction")
var restructure = require("restructure")

function sort(f, left, right) {
  var pairs = coreduction(left, right)
  return restructure(pairs, function(pair, buffer) {
    buffer = buffer.concat(pair).sort(f)
    return [buffer, buffer.shift()]
  }, [])
}

var restructure = require("restructure")

function sort(f, left, right) {
  left = map(left, function(item) { return { left: item })
  right = map(right, function(item) { return { right: item })
  var sorted = reductions(merge(left, right), function(state, item) {
    var isLeft = 'left' in item
    var value = isLeft ? item.left : item.right
    buffer.push(value)
    if (buffer.length > 1 && isLeft !== state.isLeft) {
      buffer = buffer.sort(f)
      return { buffer: buffer, value: buffer.shift(), skip: false }
    } else {
      return { buffer: buffer, skip: true }
    }
  }, { buffer: [] })

  var items = filter(sorted, function(item) { return !item.skip })
  return map(items, function(item) { return item.value })
}