vidarh

#include <stdio.h>
#include <stdlib.h>

struct closure {
  void (* call)(struct closure *);

  int x;
};

cametan001

CL-USER> (asdf:operate 'asdf:load-op :hello)
; loading system definition from /home/cametan/hello.asd into
; #<PACKAGE "ASDF0">
; registering #<SYSTEM HELLO {AB3F071}> as HELLO
NIL
CL-USER> 

dharmatech

Polymorphism in Scheme via compile time dispatch

Here's an example of polymorphism in C++:

int nth ( int a[] , int i ) { return a[i] ; }

double nth ( double a[] , int i ) { return a[i] ; }

One way to think of this is that there are two functions called nth. One can be called with an int array and the other can be called with a double array. The function that is called is determined at compile time by looking at the type of the expression of the first argument.

dharmatech

Generics in Scheme

In a previous note I demonstrated polymorphism in Scheme using Chez Scheme's compile time values and properties.

The code in that example is pretty raw; you might not want to code each generic in that manner. One approach is to decouple the signature/method table. We can do this by factoring out some code into a 'make-generic' procedure:

(define (make-generic table)
  (lambda (stx)
 (lambda (lookup)

chaoxu

default (Int, Integer, Rational, Double)

if' :: Bool -> a -> a -> a
if' True  x _ = x
if' False _ y = y

isBraidIdentity x n = 
  [1..n] == concat (map (braidReduce x) [[y] | y <- [1..n]])

braidReduce = flip (foldr homomorphism)

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

aras-p

// THIS IS ONLY A PORTION OF THE FILE
// WILL NOT COMPILE OUT OF THE BOX!



void OrthogonalizeTangent (TangentInfo& tangentInfo, Vector3f normalf, Vector4f& outputTangent)
{
	TangentInfo::Vector3d normal   = { normalf.x, normalf.y, normalf.z };
	TangentInfo::Vector3d tangent  = tangentInfo.tangent;
	TangentInfo::Vector3d binormal = tangentInfo.binormal;

nikcub

In August 2007 a hacker found a way to expose the PHP source code on facebook.com. He retrieved two files and then emailed them to me, and I wrote about the issue:

http://techcrunch.com/2007/08/11/facebook-source-code-leaked/

It became a big deal:

http://www.techmeme.com/070812/p1#a070812p1

The two files are index.php (the homepage) and search.php (the search page)

bxt

# Originally from http://sharebear.co.uk/blog/2009/09/17/very-simple-python-caching-proxy/
#
# Usage:
# A call to http://localhost:80000/example.com/foo.html will cache the file
# at http://example.com/foo.html on disc and not redownload it again. 
# To clear the cache simply do a `rm *.cached`. To stop the server simply
# send SIGINT (Ctrl-C). It does not handle any headers or post data. 

import BaseHTTPServer
import hashlib

lelandbatey

Description

This simple script will take a picture of a whiteboard and use parts of the ImageMagick library with sane defaults to clean it up tremendously.

The script is here:

#!/bin/bash
convert "$1" -morphology Convolve DoG:15,100,0 -negate -normalize -blur 0x1 -channel RBG -level 60%,91%,0.1 "$2"

Results