Page 2 of 16 for Blog

Apr 1, 2019
Use vector in ThreadScope to Reduce the Memory Usage
As described in the issue ThreadScope#29, the ThreadScope is really slow when loading a relatively huge eventlog file, and consumed an unacceptable volume of memory. High memory usage caused by using incorrect data structure is fairly common in many Haskell applications, thus at first glance, I focused on the internal data structure that ThreadScope uses when browsing the source code. I found that replacing List using Vector could bring a significant improvement.

Aug 23, 2018
Coupon Collector's Problem
The coupon collector’s problem describes the following question: there are $n$ different types of coupons and the collector will receive a random coupon every time, what is the expected trials that the collector can collect all $n$ types of coupons? We can conclude that the expected trails grows as $\mathcal{O}(n\log{n})$.

Sep 11, 2017
Join in SQL
join is a kind of SQL operation in relational algebra, combining columns cross tables.

Aug 28, 2017
Excluded Middle in Coq
Excluded middle is an important theorem in classical logic. However in intuitionistic logic, the excluded middle theory doesn’t satisfy the constructive principle. The excluded middle law is provable in Coq and often confused with some other theorems in Coq.

May 16, 2017
CNN Meets Graphs
Graph convolutional network is a kind of neural network that use graph data as input, developing a serials of Conv operator and Pooling theory based on graph theory, mainly the spectral graph theory.

Dec 26, 2016
Pattern Matching in List Comprehension
After the | in list comprehension, pattern matching can be used to filter expected values.

Oct 24, 2016
随机向量和概率统计
Oct 17, 2016
矩母函数和特征函数
概率论中，矩母函数（Moment-generating Function）和特征函数（Characteristic Function）是定义概率分布函数的另一种形式。
Oct 8, 2016
DLL的初始化和退出处理
将Haskell代码编译成动态链接库供其他语言调用时，需要调用hs_init函数初始化GHC的运行时环境，退出时需要调用hs_exit函数来完成释放内存等清理工作¹。如果把初始化和退出处理交给用户程序去做，不仅会给用户程序代码带来额外的麻烦，而且错误的初始化和退出处理还会造成调用动态链接库时的错误。DLL本身的处理化和退出清理机制可以很好地解决这一问题。
1. https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ffi-chap.html#using-the-ffi-with-ghc ↩