transducers.js

var caller = Function.prototype.bind.bind(Function.prototype.call);

var slice = caller(Array.prototype.slice);
var concat = caller(Array.prototype.concat);

function map(transform) {
  return function (combine) {
    return function (accumulator, value) {
      return combine(accumulator, transform(value));
    };
  };
}

function filter(transform) {
  return function (combine) {
    return function (accumulator, value) {
      return transform(value) ? combine(accumulator, value) : accumulator;
    };
  };
}

function compose() {
  var transducers = slice(arguments);
  return function (combine) {
    return transducers.reduceRight(function (combine, transducer) {
      return transducer(combine);
    }, combine);
  }
}

function odd(value) { return value % 2 }

function add1(value) { return value + 1 }

[9, 8, 7].reduce(compose(map(add1), filter(odd))(concat), [])