CTimmerman

""" SICP section 2.2.3, page 160.
We can rearrange the pieces and use them in computing the product of the squares of the odd integers in a sequence:

(define (product-of-squares-of-odd-elements sequence) (accumulate * 1 (map square (filter odd? sequence))))
(product-of-squares-of-odd-elements (list 1 2 3 4 5))
225

2017-09-13 v1.0 Translated & benchmarked by Cees Timmerman
"""
from __future__ import print_function  # For Python 2.

mfuerstenau

  ZigZag-Encoding
  ---------------
  
  Maps negative values to positive values while going back and
  forth (0 = 0, -1 = 1, 1 = 2, -2 = 3, 2 = 4, -3 = 5, 3 = 6 ...)

  (i >> bitlength-1) ^ (i << 1)

  with "i" being the number to be encoded, "^" being
  XOR-operation and ">>" would be arithemtic shifting-operation

dherman

Goal

Typed arrays can be copied or transferred between workers, but it's not possible for multiple workers to work with a buffer in parallel without copies. This document describes two ways to improve this without introducing data races: transferring read-write access to disjoint regions of buffers, and transferring read-only access to shared buffers/regions.

This variant of the API enables fine-grained borrowing and sharing, where a single ArrayBuffer can have multiple disjoint regions parceled out. This way individual workers can work with their regions at their original indices. This makes the API more amenable to being a compilation target.

Example

Here is an example that demonstrates sharing a read-only segment and multiple read-write segments with four separate workers.

72lions

/**
 * Creates a new Uint8Array based on two different ArrayBuffers
 *
 * @private
 * @param {ArrayBuffers} buffer1 The first buffer.
 * @param {ArrayBuffers} buffer2 The second buffer.
 * @return {ArrayBuffers} The new ArrayBuffer created out of the two.
 */
var _appendBuffer = function(buffer1, buffer2) {
  var tmp = new Uint8Array(buffer1.byteLength + buffer2.byteLength);

jlongster

;; outlet code for implementing traditional macro expansion

;; macros

(define (expand form)
  (cond
   ((variable? form) form)
   ((literal? form) form)
   ((macro? (car form))
    (expand ((macro-function (car form)) form)))

Gozala

// Lack of tail call optimization in JS
var sum = function(x, y) {
  return y > 0 ? sum(x + 1, y - 1) :
         y < 0 ? sum(x - 1, y + 1) :
         x
}

sum(20, 100000) // => RangeError: Maximum call stack size exceeded

// Using workaround