[WIP] work on concepts

README.md

@@ -42,6 +42,8 @@ There is a tool, that counts and prints exercises unlocked by each concept, and
 
 `_tools/concepts-practice.red`
 
+Recently, Exercism introduced tasks, which are just parts of an exercise. Currently, they are only possible in concept exercises. You can indicate, which tests are specific for particular task. Each track links tasks with tests [in a way maintainers find appropriate](https://github.com/exercism/docs/blob/main/building/tooling/test-runners/interface.md#task-id). In Red it is done by adding `"   task_id: 1"` at the end of the test description string in exercise test file. Notice three spaces before "task_id".
+
 ## Contact
 
 Besides creating issues and commenting in this repository, you are welcome to post on [Red's "training" Gitter channel](https://gitter.im/red/training).

concepts/basics/introduction.md

@@ -1 +1,17 @@
 # Introduction
+
+Everything you need to run Red programs and do exercises in Exercism:
+
+* Using editor
+* Running your code
+* Executing tests for exercises
+
+Red code is built from **blocks** and **values**. Block can contain values and other blocks. In fact, a block is also a value.
+
+Each value has its **type**. Block's type is `block!`. And type is also a value of type `type!`. There are lots of types in Red, like numbers, dates, tuples, urls, paths, strings, binary data, maps, vectors, emails... about a 50 of them.
+
+There are also **comments**. They start with `;` and end with end of line. Red has also block comments, but they are a different kind. In fact, they are accomplished with a function called `comment`, which takes any type of argument (can be block, string or anything) and just does absolutely nothing.
+
+Red is a homoiconic language, so it's code is actually just a data, until we **evaluate** a block. Which simply means, that we "execute" it and get value of last expression.
+
+

concepts/conditionals/introduction.md

@@ -1 +1,10 @@
 # Introduction
+
+what's "truthy"
+
+* if
+* unless
+* either
+* case
+  * default: `true` or word, like `'default`
+* switch

concepts/dsl/introduction.md

@@ -1,3 +1,11 @@
 # Introduction
 
 > Provide a brief introduction to a student who has not yet completed the corresponding concept exercise.
+
+There are various ways to implement a DSL:
+
+* define functions and run DSL as Red code
+* parse DSL as Red blocks of data
+* parse DSL strings
+
+... and any combinations of these methods.

concepts/evaluation/introduction.md

@@ -1 +1,5 @@
 # Introduction
+
+Precedence is left to right
+
+There is a fun part with comparison and math operators

concepts/functions/about.md

@@ -4,3 +4,4 @@ TODO:
 
 * Most exercises here are written as functions, because they are reusable and easy to test, which makes them perfect for separating pieces of code.
 * Function names by convention should be verbs or contain verbs.
+* In Red everything is a function, even expressions, that are keywords or operators in other languages, like `if` or `+`.