shwestrick

  * Separate compilation vs whole-program compilation. OCaml uses separate compilation and therefore has a very constrained heap object model which makes it possible to get polymorphism across separately compiled modules. In contrast, MaPLe uses whole-program compilation and therefore is able to monomorphize and optimize much more aggressively. Whole-program compilation can be slow for large projects.

  * The multicore OCaml effort was driven by backwards compatibility, especially in terms of performance -- they wanted to ensure that the performance of existing sequential OCaml code would be completely unaffected by the new run-time system.  In contrast, MaPLe focuses on efficiency and scalability for parallel code.

  * Multicore OCaml will let you implement your own scheduler, as a library, on top of coarse-grained threads. In contrast, MaPLe comes with a built-in scheduler, and it's not easy to change it.

    function nqueens(i:number, n:number, queens: number[][]) {
      if (i >= n) return 1;

      let count = 0;
      for (let j = 0; j < n; j++) {

        let is_threatened = false;
        for (let k = 0; k < queens.length; k++) {
          let x = queens[k][0];
          let y = queens[k][1];

          if (i == x || j == y || i - j == x - y || i + j == x + y) {
            is_threatened = true;
            break;
          }
        }

        if (is_threatened) continue;

        count += nqueens(i+1, n, Array(Array(i,j)).concat(queens))
      }

      return count;
    }

    combine ((a1, b1), (a2, b2))  =  (a1 * a2, b1 * a2 + b2)