jcchen jccode

Principled Meta Programming for Scala

This note outlines a principled way to meta-programming in Scala. It tries to combine the best ideas from LMS and Scala macros in a minimalistic design.

LMS: Types matter. Inputs, outputs and transformations should all be statically typed.
Macros: Quotations are ultimately more easy to deal with than implicit-based type-lifting
LMS: Some of the most interesting and powerful applications of meta-programming

Recursion and Trampolines in Scala

Recursion is beautiful. As an example, let's consider this perfectly acceptable example of defining the functions even and odd in Scala, whose semantics you can guess:

def even(i: Int): Boolean = i match {
  case 0 => true
  case _ => odd(i - 1)
}

def odd(i: Int): Boolean = i match {

From @echojc's awesome blog post and followup

Install zsh from cygwin
Install oh-my-zsh from https://github.com/robbyrussell/oh-my-zsh . Follow the manual instructions
To make zsh default on ConEmu, create a task with C:\cygwin64\bin\mintty.exe /usr/bin/zsh - . Make it the defaut shell.
To start a zsh shell on demand, add this batch script to your path or start menu or wherever.

start C:\cygwin64\bin\mintty.exe /usr/bin/zsh -

介绍

Spring从2.0开始引入了一个新的机制用于扩展xml模式，我们就可以编写自定义的xml bean解析器然后集成到Spring IoC容器中。

xml扩展大概有以下几个步骤：

编写自定义类
编写xml schema来描述自定义元素
编写NamespaceHandler新样式.css的实现类
编写BeanDefinitionParser实现类
把以上组建注册到Spring

	{
	"inbounds": [
	{
	"port": 1080,
	"listen": "127.0.0.1",
	"protocol": "socks",
	"settings": {
	"udp": false
	}
	}

	package slick.extensions

	import slick.ast._
	import slick.dbio.{ Effect, NoStream }
	import slick.driver.JdbcDriver
	import slick.jdbc._
	import slick.lifted._
	import slick.relational.{ CompiledMapping, ProductResultConverter, ResultConverter, TypeMappingResultConverter }
	import slick.util.{ ProductWrapper, SQLBuilder }

	#!/bin/bash
	# update_gfwlist.sh
	# Author : VincentSit
	# Copyright (c) http://xuexuefeng.com
	#
	# Example usage
	#
	# ./whatever-you-name-this.sh
	#
	# Task Scheduling (Optional)

	from django.core.serializers.json import DjangoJSONEncoder
	from django.template import Library
	from json import dumps as json_dumps

	register = Library()


	@register.filter
	def json(data):
	"""

	import java.util

	import org.apache.kafka.clients.consumer.KafkaConsumer

	import scala.collection.JavaConverters._

	object ConsumerExample extends App {

	import java.util.Properties