Records from 3/29 to 4/2

To be filled…

Facts about SQL

• MySQL does not support data integrity check(that is, it parses but ignores CHECK constraint).
• MariaDB was the same but started implementing it since 10.2.
• PostgreSQL is likely to support this feature.

Facts about Arch Linux

• Arch Linux has only in its official repo MariaDB 10.1 because of this.
• updpkgsums is a command line tool to update the checksums in the PKGBUILD file.
• Running makepkg with -s would install the dependencies for it, and -i would install the package built.
• trizen, aurman are also AUR helpers, the same as yaourt, pacaur.

Facts about CentOS 7

• It uses Linux 3.10.
• The packages in EPEL can be very old as well.
• The lttng package in EPEL is ver 2.4.

Fact about Oracle

It sucks.

Facts about Input Methods

• The author of Flypy(http://www.flypy.com) is stingy about the double pinyin scheme they created – they haunt every developer of an input method which make Flypy available – either as preset or configurable afterwards – without their authorization.

• Rime, GBoard, and MS IME seem not (yet) in trouble.

• The author of Flypy criticized others’ approach to tackle zero-consonant characters(‘a’, ‘er’, ‘ou’, etc.) from their perspective. Flypy uses the first and the last letter of the syllable(‘ee’ for ‘e’, ‘ag’ for ‘ang’, etc.), while some others allocate a specific letter, say, ‘o’, for it.(That is, ‘oa’ for ‘a’, ‘ol’ for ‘ai’ for MS).

• A family of double pinyin derives from Ziranma, with minor differences. MS and Sogou are among them.

• Mozc could be configured using /usr/lib/mozc/mozc_tool --mode=config_dialog, where the input mode could be switched between Romaji and Kana.

Misc

空はきれいなのに

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The video game developer, Compile Heart Inc., has recently announced its bankruptcy, according to Noirina International Reports. The developer who’s had the hands on War of Agarest series, the franchise of Neptunia, has finally meet its fate because of its overspending and decision mistakes.

Compile Heart was a video game developer, set up as the complete subsidiary of Idea Factory by Shingo Kuwana, who was the CEO of Idea Factory. It was more like a brand than a child company of IF, just like how FAVORITE and Omega-Star were to CROSSNET. When Compile Heart focused on moe games, another brand of IF, Otomate, majored in Otome games, as its name suggests.

Year 2015 witnessed a major success of Compile Heart, when the Megadimension Neptunia was launched. The game, features three stories in three dimensions, was said to be well crafted and organized. Though not perfectly, the game is still a complete embodiment of the spirits of Neptunia series.

However, after 2015, Compile Heart has ceased the development of any canon Neptunia games, instead, there were only three spin-offs launched in the following years: Megatagmension Blanc+Neptune VS Zombies, Superdimension Neptune VS Sega Hard Girls, and Cyberdimension Neptunia. Even those are not full-fledged Neptunia games as the previous four, they are still completed, having their own good plots(except the first one and the last one). Also, the first and the last of them are good explorations into a brand new genre that Compile Heart has never set its foot in, rather than staying within its RPG confort zones(and still never now, because these action games were developed by Tamsoft, the maker of Senran Kagura). But they received positive reviews from customers over the world, although seen not as good as the canon ones.

And Compile Heart just took a step further. It decided to entrust a Carribean game studio, AmateurGameStudios the next game of Neptunia series. The studio gave it a tentative title: Villain Neptune. According to its settings, the evil Neptune, the protagonist in the game, crushed one of the three dimensions, making the whole game a 2D one. It was purported that they were making a Megaman Maverick Hunter X at first, but ended up with another Odin Sphere. And its quality was severely compromised probably because of this sudden change during the game making.

So it came as no surprise that the Evil Neptune(the name when it was launched) did not receive much acclaim. However, Compile Heart erroneously attributed its failure to the assumption that Neptunia was losing its momentum. And it decided to make new IPs. In this period, they made the Fairy Fencer F, Genkai Toki, Mugen Souls Z, and so on. They had attempts with not only role playing games, but card games and adventure games as well. However, none of them made enough profits to reverse the situation. . The economical crisis in Spring 2018 added to the difficulty for the company to operate. On 4/1/2018, Sunday, Compile Heart issued an application for bankruptcy to Tokyo District Court. Its property rights of Neptunia and other series go to Idea Factory Co., Ltd. And one of the company’s previous member, Masamitsu Niitani, is going to start a new game maker called Compile(the brand name and the heart symbol still belong to IF, so he cannot use it). And Takashi Takeuchi, the founder of Type-Moon, is showing his willingness to join the new company’s graphics team.

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Facts about Bash/Dash/sh

• Arch Linux uses Bash(Bourne Again Shell) for POSIX shell (/bin/sh)
• When Bash is called with sh, it tries to emulate the POSIX shell
• Dash is POSIX compatible, making it Bash incompatible.

Facts about of V-Table

In C++, the virtual table pointer is located in the head of the class instance.

The virtual table is a table of pointer to virtual(overridden or not) functions.

Therefore, to invoked these virtual methods, a mechanism called thunk(a jocular form of think) is needed. It means doing something before the actual function is called. And functional language relies largely on this mechanism.

Fact about Zeromq

• It is a distributed communication library.
• It sits on top of the TCP/IP layer, means the possibility is huge that it sends message by syscalls like send.

Facts about lttng

• Means Linux Tracing Tool, next generation
• In Artful repo, for older Ubuntu versions, go to ppa:lttng
• Can be used to trace syscall, or even user application(need to write code into the program)
• babeltrace could be used to translate the file.

Facts about Ubuntu

• The life span of Zesty(17.04) has ended in Jan. 2018. Artful will meets its end in Jul. 2018.
• The life span of non-LTS versions is 9 months.
• 18.04 is called Bionic, will upgrade later

Facts about Opam

The package manager of OCaml. Not a kind of mineral.

Facts about type algebra

Refer to this page.

The type could be expressed in an algebra-like manner:

0: None type, there is 0 way to construct an empty type object

1: Singleton

2: Two ways to construct the type, boolean type is an example

And as a surprising yet unsurprising coincidence, the sum and product obey the rules:

Communicative: $a+b=b+a$

Associative: $a+(b+c)=(a+b)+c$

Distributive: $a\times(b+c)=a\times b+a\times c$

For recursive types like the tree, which is

data Tree a = Leaf a | Branch (Tree a) (Tree a)

The formula is:

Therefore, we have:

Use Taylor series, we could obtain:

And the coefficients of a are Catalan numbers.

Zippers means we could turn the pocket inside out and focus on one element in a data structure, in a way that updating the focused element , as well as moving the focus around, takes $O(1)$ time.

And we can focus on the holes of a type.

It is likened to partial differentiation, for example:

If $\frac{\partial t}{\partial a}$ means the hole numbers of a in t, and let the g of constant be zero, and g of other variables be one, then magic!

It can be applied to the list type:

data List a = [] | Cons a (List a)

Added 3/29:

But the same thing could not be perfectly applied to the binary tree type.

Recall, we have the binary tree type:

data Tree a = Leaf | Branch a (Tree a) (Tree a)

Then the formula is:

The best I could get is about:

According to LYAHFGG, the zipper of a binary tree should be something like this:

data Crumbs a = LeftCrumb a (Tree a) | RightCrumb a (Tree a)
type BreadCrumbs a = [Crumbs a]
type Zipper a = (Tree a, Breadcrumbs a)  

It is easy to see that Crumbs a has a type of $2aT$ and BreadCrumbs a has a type of $\frac{1}{1-2aT}$.

But wait! That gives $T$ rather than a $T^2$ in the numerator.

Maybe we’ve just started wrong, like, we took the wrong differentiation.

That would be left for future investigation.

Misc

PEBKAC (Problem Exists Between Keyboard And Chair) is the word that describes user error.

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