chaitanyagupta

Reader Macros in Common Lisp

This post also appears on lisper.in.

Reader macros are perhaps not as famous as ordinary macros. While macros are a great way to create your own DSL, reader macros provide even greater flexibility by allowing you to create entirely new syntax on top of Lisp.

Paul Graham explains them very well in [On Lisp][] (Chapter 17, Read-Macros):

The three big moments in a Lisp expression's life are read-time, compile-time, and runtime. Functions are in control at runtime. Macros give us a chance to perform transformations on programs at compile-time. ...read-macros... do their work at read-time.

ragingwind

Backend Architectures

Twitter

ror, scala, jetty, erlang, thrift, mongrel, comet server, my-sql, memchached, varnish, kestrel(mq), starling, gizzard, cassandra, hadoop, vertica, munin, nagios, awstats

• Introduce Gizzard of Twitter - 트위터의 새로운 분산 관리 라이브러리 Gizzard를 소개합니다.
• The Architecture Twitter Uses to Deal with 150M Active Users, 300K QPS, a 22 MB/S Firehose, and Send Tweets in Under 5 Seconds
• Scaling Twitter: Making Twitter 10000 Percent Faster

vmg

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <float.h>
                                    int  main
                                    (int argc
         ,char *ac         []){int i, count =                  argc - 1;
         double  *         dvalues=malloc(01-                  01+count*
sizeof(double)+1);         double mi=DBL_MAX,ran=.0,ma         =DBL_MIN,mo;for(i=         00; argc>1
&&i<count;i=i+8-7)         {double val = atof(ac[i+1])         ;if(23&&val<mi)mi=         val;if(val