@ig3/srf - Spaced Repetition Flashcards

It is 2 years since I gave up on Anki and wrote @ig3/srf.

I have used it to study almost very day, for 2 years now. I have changed the scheduling algorithm several times. Sometimes little tweaks of parameters and sometimes fundamental changes to the algorithm.

The most recent big change was to eliminate the percentage of correct answers as a factor in calculating the new interval. Instead, for each review of a card with interval longer than the learning threshold, the interval and due date of every card with interval longer than the learning threshold is adjusted, according to the difference between percent correct and the target percent correct. This decreases the delay of feedback. It's early days, but it seems to be working.

Overall I am very pleased with @ig3/srf. I am limited by my poor memory but not overwhelmed and not feeling like a failure. At least, not most days. There are some days, usually after a few days without sleep, that it truly seems hopeless. But then I get some rest and get back on track.

I have put a lot of time into development @ig3/srf over the past two years, but I am confident that it was less effort for a better outcome than trying to maintain my Anki plugin to improve Anki's algorithm. I don't regret my decision at all.

apt update failing with connection failed

Today, attempting apt update was failing:

Hit:1 http://deb.debian.org/debian bullseye InRelease
Err:2 http://security.debian.org/debian-security bullseye-security InRelease
  Connection failed [IP: 151.101.166.132 80]
Err:3 http://deb.debian.org/debian bullseye-updates InRelease
  Connection failed [IP: 151.101.166.132 80]
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
All packages are up to date.
W: Failed to fetch http://deb.debian.org/debian/dists/bullseye-updates/InRelease  Connection failed [IP: 151.101.166.132 80]
W: Failed to fetch http://security.debian.org/debian-security/dists/bullseye-security/InRelease  Connection failed [IP: 151.101.166.132 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.

I was able to access the resources in my browser, which was redirected to https.

So I updated /etc/apt/sources.list, changing http to https throughout and then apt update completed without errors.

Hit:1 https://deb.debian.org/debian bullseye InRelease
Get:2 https://deb.debian.org/debian bullseye-updates InRelease [44.1 kB]
Get:3 https://security.debian.org/debian-security bullseye-security InRelease [48.4 kB]
Get:4 https://security.debian.org/debian-security bullseye-security/main Sources [192 kB]
Get:5 https://security.debian.org/debian-security bullseye-security/main amd64 Packages [236 kB]
Get:6 https://security.debian.org/debian-security bullseye-security/main Translation-en [154 kB]
Fetched 675 kB in 5s (138 kB/s)                            
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
68 packages can be upgraded. Run 'apt list --upgradable' to see them.

The original sources had been working for well over a year. It seems http is no longer supported.

@ig3/couchapp is deprecated

 @ig3/couchdb is deprecated.

It works with CouchDB 3.x but vhost and rewrite rules are deprecated and planned to be removed from CouchDB 4. Without them, couchapps will not work.

The primary feature of a couchapp is that it is served from a CouchDB server. No other server is required.

The concept of a CouchApp arose with CouchDB. But, as the CouchDB docs indicate, CouchApps are deprecated:

Note: Previously, the functionality provided by CouchDB’s design documents, in combination with document attachments, was referred to as “CouchApps.” The general principle was that entire web applications could be hosted in CouchDB, without need for an additional application server.

Use of CouchDB as a combined standalone database and application server is no longer recommended. There are significant limitations to a pure CouchDB web server application stack, including but not limited to: fully-fledged fine-grained security, robust templating and scaffolding, complete developer tooling, and most importantly, a thriving ecosystem of developers, modules and frameworks to choose from.

The developers of CouchDB believe that web developers should pick “the right tool for the right job”. Use CouchDB as your database layer, in conjunction with any number of other server-side web application frameworks, such as the entire Node.JS ecosystem, Python’s Django and Flask, PHP’s Drupal, Java’s Apache Struts, and more.

Several tools have been written to automate building and deploying CouchApps. The earliest I know about were developed by Chris Anderson. Some history is available in the post: What is Couchapp?.

I had been using a node based implementation of the couchapp tool but when I set up a new CouchApp early 2022 I found it no longer worked. I forked it and released @ig3/couchapp but learned that CouchDB had deprecated the features that make CouchApps possible.

So I rebuilt my CouchApp / couchapp based apps using a combination of nginx and CouchDB.

It isn't hard.

Everything comes from nginx:

 * static content is served by nginx directly

 * CouchDB access is proxied by nginx

 * Rewrite rules are written in nginx

 A very simple app might be configured in nginx as:

server {
  server_name mycoucnapp.example.com;
  listen 443 ssl http2;

  client_max_body_size 8M;

  location / {
    root /usr/local/data/mycouchapp/attachments;
    try_files $uri /index.html;
  }

  location /couchdb {
    proxy_pass http://localhost:5984/;
  }
  location /couchdb/ {
    proxy_pass http://localhost:5984/;
  }
}

Note the trailing slashes on the URLs to proxy_pass. They are 
significant. Without them, the entire request path is passed to CouchDB.
With them, the / replaces the location (/couchdb or /couchdb/). 

How I study Chinese

 Just a few notes on how I study Chinese.

I study daily using Spaced Repetition Flashcards (a.k.a. srf). About an hour per day.

I started using Anki, but I found the algorithm didn't work for me, causing me to become overwhelmed with big backlogs that I couldn't get through and I had to manually adjust new cards. The algorithm of srf works better for me and it regulates new cards automatically.

But there are many programs for presenting flashcards and any of them can work.

Because I started with Anki, I started with a few Anki decks. One of characters, one of Chinese provinces and cities, and one of words and sentences. I have added many of my own cards, mostly from videos I have watched.

I find the sentences harder to learn initially but easier in the long term. Individual characters are too abstract, with too many unrelated meanings. As I progress, it seems more important and more effective to be able to recognize them in the context of words (combinations of two or more characters) and sentences. Even if I knew all the meanings related to each individual character, it often leaves me unsure about the meaning of a word or sentence or, worse, with the wrong interpretation.

I watch a lot of Chinese videos with English and Chinese subtitles. Mostly modern drama with, I hope, modern vocabulary and accent.

A few years ago, when I started, I had a lot of difficulty finding good videos with clear audio and good subtitles. More recently there is a lot of good content. YouTube has many channels of good content. More than I can watch. I sometimes watch videos from Chinese sites, but many of them aren't available to me or require setting up accounts, so I don't bother. There's enough content on the free sites.

I have begun reading. I use Calibre to maintain a library of epub books but I view them in my Firefox browser using calibre-web to serve them and the @ig3/zhongwen add-on for lookup of Chinese characters.

The @ig3/zhongwen add-on is available from the Firefox add-ons website.

I use @ig3/zhongwen rather than the Zhongwen add-on because @ig3/zhongwen supports lookup of content in iframes and calibre-web presents the epub content in iframes, so the Zhongwen add-on doesn't work. I have also improved the positioning of the pop-up in @ig3/zhongwen so it doesn't cover the selected characters.

With a local Calibre library and calibre-web running on my laptop, I can read Chinese with character lookup even when I'm offline.

I'm old. My memory isn't as good as it used to be. But I am making progress learning Chinese. The stats in srf make this clear and also, when I watch videos or listen to conversations of native Chinese speakers, I can't yet follow but I begin to catch words and phrases and understand them without consciously translating them. It's always a thrill when I clearly get the meaning without having to think about it.

I only use Firefox, not Chrome, Safari, Opera or any other browser. While calibre-web might work from other browsers, I haven't tried and don't intend to support using @ig3/zhongwen from other browsers.  In particular, I have not published it as a Chrome add-on, as the original Zhongwen add-on is. I have submitted a patch to the Zhongwen add-on maintainer, for support of content in iframes, but have had no response to it and it hasn't been merged. Since then, I have made several more changes to @ig3/zhongwen, including a revision of how iframes are supported, making support more reliable.

I also produce my own epub documents for study. I first put the text into Markdown files then I use a simple script to convert collections of Markdown files (one per chapter) into an epub file that I can load into my Calibre library and review with calibre-web and the @ig3/zhongwen add-on.

There's plenty of Chinese content on the Internet, including many books and novels available as epub documents or easily converted to epub documents. The @ig3/zhongwen add-on doesn't work directly on all sites. Some don't allow selection of text at all. I also find it convenient to be able to review when I'm offline, which I can do if I have copied the text to make my own epub documents. A little collection that I can review as many times as I need to.

While @ig3/zhongwen is easy and very helpful, its definitions don't always help and miss the broader context. Sometimes, for example, I don't know how to break down a sentence into the correct words and phrases. While it is probably obvious to a Chinese person, I often find that there are several overlapping possibilities. I find Google Translate very helpful for understanding the meaning and structure of whole sentences.

With Google Translate, what I sometimes do is copy in a whole sentence, then split it onto multiple lines in the input box to make sure I am correct about what the words and phrases are.

The MDBG website, from which the dictionary used by @ig3/zhongwen comes, is very helpful, with various lookup functions. 

The stroke diagrams on the MDBG website are great! Though the count of strokes is sometimes nonsense. I think the discrepancies of stroke counts come from MDBG adding up counts of radicals in their traditional forms when the character has them in simplified form, with fewer strokes. Or sometimes simply errors. I try not to get hung up on the stroke counts, but I do try to learn the 'correct' stroke order and direction. Teaching sites for hand writing seem to emphasize stroke order and direction very much.

How to clean greasy scouring pads (Scotch-Brite and equivalent)

 I use scouring pads to clean pots and pans in the kitchen. They are like magnets for oil and grease which gets into them and won't come out with dish detergent. For a long time I was throwing them out when they became greasy but I didn't like the waste.

Today I discovered that a bit of caustic soda / sodium hydroxide removes the oil and grease very quickly and doesn't seem to damage the pads at all, leaving them clean and oil free.

Put a little cold water in a small pot. Add a little caustic soda - maybe half a teaspoon. Put in the pad and heat to a simmer for a few minutes, stirring occasionally.

Be very careful with the caustic soda. It is a powerful chemical that can cause burns. Instructions say to add it to cold water, not hot. When it mixes with water, it produces a lot of heat. Instructions say NEVER ADD WATER TO CAUSTIC SODA. Always add caustic soda to cold water.

Fool that I am, I added the caustic soda to hot water. Only a little at a time. Each time, it boiled up. Good thing it was only a little. I'll start with cold water next time.

But almost immediately, I could see the oil and grease coming out of the pad. The water went dark with it. I left it to simmer for maybe 5 minutes, stirring it around a few times. Then I rinsed it out with lots of cold water before touching it.

Caustic soda is a strong base. It can burn you. Handle it carefully. Don't get it on your skin. Don't get water with too much caustic soda on your skin. Definitely don't let it splash in your eyes. Rinse with plenty of water.