Turning notes into flashcards, or should I say concards! This is my ongoing attempt to make flashcards more simple and convenient. Concards provides much of the functionality of other mainstream flashcard applications, but with a unique focus on parsing cards embedded within text files.

Features

• Spaced repetition similar to SM2!
• UTF-8 as a first-class citizen!
• Configure with your favorite editor!
• Undo & Redo support!
• Read from directories or files!
• Reversible cards!
• Cloze cards!

Install

Download the latest release from the release page. At the moment, only Linux and Mac are supported.

You can also build a snapshot from source with the go command.

$ go install github.com/alanxoc3/concards

Once installed, you may want to try running concards on this readme!

$ concards README.md

You may also want to review the help command's output.

$ concards --help

Basic Syntax

You can learn the full flashcard embedding syntax in just a few minutes! Let's get started.

Creating a flashcard

To make a flashcard, you must put the flashcard text within a concards block. A concards block looks like this #: :#, where text would be placed between the two colons. Ex:

#: This is a one sided flashcard. :#

The text above will produce a one sided flashcard! But flashcards are normally 2 sided, so let's create a new flashcard that separates a question and answer with the pipe symbol:

#: What is a great way to decrease the effects of the forgetting curve?
 | Spending time every day to review previously learned information. :#

Any number of sides are supported, so creating a 3 sided flashcard is a piece of cake:

#: What are Newton's 3 laws of motion?
 | 1. An object at rest stays at rest unless acted upon.
 | 2. Force is equal to mass times acceleration.
 | 3. For every action, there is an equal and opposite reaction. :#

You can either create new blocks for each card, or you can keep them in the same block. This creates 2 cards:

#: Who published the first flashcards? | Favell Lee Mortimer
#: When were the first flashcards published? | 1834 :#

Reversible Cards

When learning a language, you might find yourself writing a flashcard that transitions a phrase from language #1 to language #2 and writing another flashcard that transitions the same phrase from language #2 to language #1. Concards makes this easier with the :: operator

#: saluton al la mundo :: hello world :#

Generates these cards:

#: saluton al la mundo | hello world
#: hello world | saluton al la mundo :#

If you are learning two languages, you can expand this with an extra :::

#: spagetoj :: spaghetti :: 意面 :#

Generates these cards:

#: spagetoj | spaghetti | 意面
#: spaghetti | spagetoj | 意面
#: 意面 | spagetoj | spaghetti :#

Translating a word from one language to another often results in multiple definitions. Concards can represent these scenarios more efficiently when combining the | and ::.

#: apricot | almond :: 杏仁 :#

Generates these cards:

#: apricot | 杏仁
#: almond | 杏仁
#: 杏仁 | apricot | almond :#

The double colon operator always takes precedence before the pipe operator.

Cloze Cards

Cloze cards are handy when working with phrases or related facts. In concards, a cloze is created by putting text within a set of curly braces. Concards will generate cards from the text in the curly braces and replace the text with an empty set of curly braces.

#: {Hermann Ebbinghaus} published his findings on the forgetting curve in {1885}. :#

Generates these cards:

#: {} published his findings on the forgetting curve in 1885. | Hermann Ebbinghaus
#: Hermann Ebbinghaus published his findings on the forgetting curve in {}. | 1885 :#

Cloze nesting is supported:

#: {Education is the {kindling of a flame}}, {not the {filling of a vessel}}. :#

Generates these cards:

#: {}, not the filling of a vessel. | Education is the kindling of a flame
#: Education is the {}, not the filling of a vessel. | kindling of a flame
#: Education is the kindling of a flame, {}. | not the filling of a vessel
#: Education is the kindling of a flame, not the {}. | filling of a vessel :#

You can replace consecutive curly braces with the colon operator. This especially makes separation within a single word look nicer.

#: {Pneumono:ultra:microscopic:silico:volcano:coniosis} :#

Is the same as:

#: {Pneumono}{ultra}{microscopic}{silico}{volcano}{coniosis} :#

And generates these cards:

#: {}ultramicroscopicsilicovolcanoconiosis | Pneumono
#: Pneumono{}microscopicsilicovolcanoconiosis | ultra
#: Pneumonoultra{}silicovolcanoconiosis | microscopic
#: Pneumonoultramicroscopic{}volcanoconiosis | silico
#: Pneumonoultramicroscopicsilico{}coniosis | volcano
#: Pneumonoultramicroscopicsilicovolcano{} | coniosis :#

To group multiple clozes together, use the hash symbol before a set of curly braces.

#: #{Sebastian Leitner} published about the Leitner System in #{1972}. :#

Generates this card:

#: {} published about the Leitner System in {}. | Sebastian Leitner | 1972 :#

Cloze groups are different based on the number of hash symbols before the curly brace. Here is an example with 3 cloze groups:

#: ###{Spaced repetition} is an #{evidence-based} learning technique which
   ##{incorporates} increasing time intervals between each ##{review} of a
   flashcard in order to exploit the ###{psychological} #{spacing effect}. :#

Generates these cards:

#: Spaced repetition is an {} learning technique which incorporates increasing
   time intervals between each review of a flashcard in order to exploit the
   psychological {}.
 | evidence-based
 | spacing effect

#: Spaced repetition is an evidence-based learning technique which {}
   increasing time intervals between each {} of a flashcard in order to exploit
   the psychological spacing effect.
 | incorporates
 | review

#: {} is an evidence-based learning technique which incorporates increasing
   time intervals between each review of a flashcard in order to exploit the {}
   spacing effect.
 | Spaced repetition
 | psychological :#

Finally, you can combine the cloze syntax with :: and |:

#: {新型:冠状:病毒} :: Coronavirus | COVID-19 :#

Generates these cards:

#: {}冠状病毒 | 新型
#: 新型{}病毒 | 冠状
#: 新型冠状{} | 病毒
#: 新型冠状病毒 | Coronavirus | COVID-19
#: Coronavirus | 新型冠状病毒
#: COVID-19 | 新型冠状病毒 :#

Whitespace & Escaping

Concards ignores consecutive whitespace. The following flashcards are equivalent:

#: {Piotr A. Woźniak} created the SM-2 spaced repetition algorithm in {1987}.
#: { Piotr A. Woźniak } created the SM-2 spaced repetition algorithm in { 1987}.
#:{Piotr A. Woźniak }created the SM-2 spaced repetition algorithm in{ 1987}. :#

Generates these cards:

#: {} created the SM-2 spaced repetition algorithm in 1987. | Piotr A. Woźniak
#: Piotr A. Woźniak created the SM-2 spaced repetition algorithm in {}. | 1987 :#

Backslash any reserved character or whitespace to include it in the card text:

#: Which characters are special in concards?
 | \# \: \| \{ \}

#: Leave my door open just a crack\
Cause I feel like such an insomniac\
Why do I tire of counting sheep?\
When I'm far too tired to fall asleep
 | Fireflies, by Owl City :#

File Structure

Concards follows the XDG standard for config/data file placement.

Config Directory

The config directory is calculated by following this order of steps until one succeeds:

1. concards --config-dir <directory>
2. $CONCARDS_CONFIG_DIR
3. $XDG_CONFIG_HOME/concards
4. $HOME/.config/concards
5. ./

Hooks

Hooks are currently an experimental feature. Concards hooks works similar to git hooks. You must place an executable file with a specific name in <config-dir>/hooks/. Hooks that begin with event- are meant to be run in parallel with concards and perform tasks that don't affect concards directly. Hooks that begin with hook- are similar to plugins in that they are meant to change program behavior.

Here are all the currently supported hooks:

• hooks/event-review - executed right after passing off a card with a pass or fail
• hooks/event-startup - executed once if/when concards starts the GUI up successfully

Data Directory

The data directory is calculated by following this order of steps until one succeeds:

1. concards --data-dir <directory>
2. $CONCARDS_DATA_DIR
3. $XDG_DATA_HOME/concards
4. $HOME/.local/share/concards
5. ./

Concards has a very simple file structure. This section explains the content of the meta data files concards writes to after a review session.

The Predict File

The predict file is located at <data-dir>/predict. This file contains information needed to make a prediction when you should review a card next.

Here is an example predict file:

002141b9b9448a257b05da1f2eb78972 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 2 1 1 sm2
3dda75cb44ed447186834541475f32e2 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 1 3 -2 sm2

Here is that same file, but annotated:

sha256sum cut in half            | next timestamp       | previous timestamp   | total yes count | total no count | current streak | spaced repetition algorithm used
---------------------------------+----------------------+----------------------+---+---+----+----
002141b9b9448a257b05da1f2eb78972 | 2020-08-08T18:00:17Z | 2020-08-02T18:00:17Z | 2 | 1 |  1 | sm2
3dda75cb44ed447186834541475f32e2 | 2020-08-08T18:00:17Z | 2020-08-02T18:00:17Z | 1 | 3 | -2 | sm2

The Outcome File

The outcome file is located at <data-dir>/outcome. This file contains the historical outcomes of every time a card has been passed off or failed. It differs only slightly from the predict file. Here is the corresponding outcome file for the predict file example above:

002141b9b9448a257b05da1f2eb78972 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 0 0 0 0
002141b9b9448a257b05da1f2eb78972 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 0 1 -1 1
002141b9b9448a257b05da1f2eb78972 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 1 1 0 1
3dda75cb44ed447186834541475f32e2 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 0 0 0 1
3dda75cb44ed447186834541475f32e2 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 1 0 1 0
3dda75cb44ed447186834541475f32e2 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 1 1 0 0
3dda75cb44ed447186834541475f32e2 2020-08-08T18:00:17Z 2020-08-02T18:00:17Z 1 2 -1 0

You can notice that there are two main differences from the predict file:

• There are usually multiple lines with the same hash.
• The last column is a boolean "pass or fail" instead of an algorithm name.

Dependencies

Concards currently depends on these libraries:

• stretchr/testify for unit tests.
• spf13/cobra for CLI options.
• nsf/termbox-go for the terminal gui.
• go-cmd/cmd for hook support.
• mattn/go-runewidth to help with Asian characters.

Concards wouldn't be where it is today without those repositories & their contributors, so please check them out too!

Future Work

The next big things to focus on:

• Improved CLI UI.
• Local Web Server UI.
• Support Unix Piping.
• Customizable Algorithm Plugin System.