可能很多人没有意识到，函数式编程（FP）有两种非常不同的路线。

一条路线，为类型疯狂。这条路线的语言以Haskell为代表。这种FP，一切以类型为
中心，编程的主要任务，是要把类型搞对了，让编译器高兴，号称是“如果程序编译通
过了，程序就是对的”。这条线来自学术界，有很长的历史，是FP的主流路线，有很多
其他FP语言以此为模版。科班出身的同学们说到FP，说的就是这条路线的FP。可能他们
上学的时候学过Haskell，甚至可能还给Haskell课当过助教，但是他们恨死了Haskell
。所以这些同学们，是打死不信FP能实用的。

Discourse is a modern forum software that is quite popular in the technology circle. One can install a Discourse server easily with the recommended method of using docker. All the services needed by the Discourse server, e.g. Postgresql and Redis, will be running inside a docker container, which is fine for a small installation. However, if one has already an external Postgresql server running, e.g.

How to modify on-premise sentry server docker recipe to allow authentication using freeIPA as a LDAP provider. This post shows the steps.

Describe settings needed for using freeIPA as a LDAP security realm provider, and some cautions.

Show how to install and configure freeIPA server and clients in AWS EC2 using Route53. Point out several important issues.

How to install Ecobee3 smart thermostat when one of the existing wire connection is labeled K on the old device? This is problematic because K wire does not appear in the Ecobee3's documentation, nor in the on screen menu. I found a solution: simply connect the K wire to Y1, then enable the G connection on Ecobee3 configuration screen.​

Since Drupal 6 is no longer supported, I upgraded this site to the lasted version of Drupal 8.4.2 by following the guide. As you can see, the upgrade mostly worked. However, there are a few points of caution as well as some unresolved problems.

The list of items contained in our diaper bag for air travel, annotated with how essential each item was based on our experience as follows:

*** Must have

**   Nice to have

*     Not needed

For travel gear that may not fit in your diaper bag, please visit this page.

• Portable changing pad (***)

This is definitely essential for both in the airports as well as on the airplane. We like our JJ Cole Collections Changing Clutch.

We traveled with Boyan, our 13-month son last month to Japan (for those who are wondering, yep, he is the main reason why this blog has been so quiet in the past couple of years. :-)) and spent a unforgettable 10 days there. Before I went there, I searched over the web for tips, but they seemed to scattered around. I therefore decided to share our experience and hope it will be useful for others.

To make the information most useful, I will just list items we brought with us for the trip and comment on how essential each item was based on our experience denoted in the following way:

*** Must have

**   Nice to have

*     Not needed

1. Travel Gears

JSON is arguably the world's most popular human readable data format today.  It has largely replaced XML as the data exchange format on the Internet. One of the key reasons for the proliferation of JSON is its simplicity.  The data structure are very limited: only arrays, enclosed with []; and objects, enclosed with {}. That's it. It cannot be simpler.

Apparently, this dead simple data format is enough to represent the vast landscape of data that JSON becomes the de-facto data format for Web services. Most Web APIs we use today speaks JSON. However, JSON is not native for most programming languages. It becomes a pain to convert to and back from JSON in programming languages.