.js

function compose(first, second) {
  return function(data) {
    return second(first(data));
  }
}

function composeAll(functions) {
  return functions.reduce(compose);
}

function inc(a) {
  return a + 1;
}

function double(a) {
  return a * 2;
}

function square(a) {
  return a * a;
}

var pipeline1 = composeAll([inc, double, square]);
var pipeline2 = composeAll([double, inc, square]);

pipeline1(2); // => square(double(inc(2))) === 36
pipeline2(2); // => square(inc(double(2))) === 25

function branch(predicate, ifTrue, ifFalse) {
  return function(data) {
    return predicate(data) ? ifTrue(data) : ifFalse(data)
  }
}

function greaterThan(x) {
  return function(y) {
    return y > x;
  }
}

var pipeline3 = composeAll([inc, branch(greaterThan(3), double, square)]);
var pipeline4 = composeAll([double, branch(greaterThan(3), inc, square)]);

pipeline3(2); // => square(inc(2)) === 9
pipeline4(2); // => inc(double(2)) === 5