Newtypes for richer type hinting of Matt Pryor's Lazy\Sequence library

gistfile1.php

<?php

// Some newtypes that allow for richer type hinting in Matt Pryor's Lazy\Sequence library. https://bitbucket.org/mkjpryor/lazy-sequence/wiki/Home 

interface ArrayInterface extends Traversable {

}

class Finite implements IteratorAggregate, ArrayInterface {

  private $generator;

  public function __construct( Traversable $g ) {
    $this->generator = $g;
  }

  public function getIterator() {
    return $this->generator;
  }
}

class Infinite implements IteratorAggregate, ArrayInterface {

  private $generator;

  public function __construct( Traversable $g ) {
    $this->generator = $g;
  }

  public function getIterator() {
    return $this->generator;
  }
}

function repeatx($x) {
  $f = function($x) {
    for(;;) {
      yield $x;
    }
  };
  return new Infinite( $f($x) );
}

function takex($seq, $n) {
  $f = function($seq,$n) {
    $i = 0;
    return takeWhile($seq, function() use($n, &$i){
      $i++;
      return $i <= $n;
    });
  };
  return new Finite($f($seq,$n));
}

function takeWhile($seq, callable $predicate) {
  $f = function($seq, callable $predicate) {
    foreach( $seq as $item ) {
      if( !call_user_func($predicate, $item) ) {
        break;
      }

      yield $item;
    }
  };
  return new Infinite($f($seq,$predicate));
}

function reduce(Finite $seq, callable $reducer, $initial) {
  $accum = $initial;

  foreach( $seq as $item ) {
    $accum = call_user_func($reducer, $accum, $item);
  }

  return $accum;
}

// Some tests

foreach( takex(repeatx(1),5) as $d) {
    var_dump($d);
}

// Works
var_dump(reduce(takex(repeatx(1),5),function($x,$y) { return $x+$y; },''));

// Type error!
var_dump(reduce(repeatx(1),function($x,$y) { return $x+$y; },''));