added lecture 7

Author: pevnak

docs/make.jl

@@ -48,6 +48,7 @@ pages = [
         "4: Package development, unit tests & CI" => "lecture_04/lecture.md",
         "5: Performance benchmarking" => "lecture_05/lecture.md",
         "6: Language introspection" => "lecture_06/lecture.md"
+        "7: Macros" => "lecture_07/lecture.md"
     ]),
     "Labs" => add_prefix("./lectures", [
         "1: Introduction" => "lecture_01/lab.md",
@@ -56,6 +57,7 @@ pages = [
         "4: Package development, unit tests & CI" => "lecture_04/lab.md",
         "5: Performance benchmarking" => "lecture_05/lab.md",
         "6: Language introspection" => "lecture_06/lab.md"
+        "7: Macros" => "lecture_07/lab.md"
     ]),
     "Homeworks" => add_prefix("./lectures", [
         "1: Introduction" => "lecture_01/hw.md",
@@ -64,6 +66,7 @@ pages = [
         "4: Package development, unit tests & CI" => "lecture_04/hw.md",
         "5: Performance benchmarking" => "lecture_05/hw.md",
         "6: Language introspection" => "lecture_06/hw.md"
+        "7: Macros" => "lecture_07/hw.md"
     ]),
 
     "Projects" => add_prefix("./projects", [

docs/src/lectures/lecture_07/hw.md

@@ -0,0 +1,53 @@
+# [Homework 7: Creating world in 3 days/steps](@id hw07)
+
+## How to submit
+Put all the code of inside `hw.jl`. Zip only this file (not its parent folder) and upload it to BRUTE. You should assume that only
+```julia
+using Ecosystem
+```
+will be put before your file is executed, but do not include them in your solution. The version of `Ecosystem` pkg should be the same as in [HW4](@ref hw4).
+
+```@raw html
+<div class="admonition is-category-homework">
+<header class="admonition-header">Homework (2 points)</header>
+<div class="admonition-body">
+```
+Create a macro `@ecosystem` that should be able to define a world given a list of statements `@add # $species ${optional:sex}`
+```julia
+world = @ecosystem begin
+    @add 10 Sheep female    # adds 10 female sheep
+    @add 2 Sheep male       # adds 2 male sheep
+    @add 100 Grass          # adds 100 pieces of fully grown grass
+    @add 3 Wolf             # adds 5 wolf with random sex
+end
+```
+`@add` should not be treated as a macro, but rather just as a syntax, that can be easily matched.
+
+As this is not a small task let's break it into 3 steps. (These intemediate steps will also be checked in BRUTE.)
+1. Define method `default_config(::Type{T})` for each `T` in `Grass, Wolf,...`, which returns a named tuple of default parameters for that particular agent (you can choose the default values however you like).
+2. Define method `_add_agents(max_id, count::Int, species::Type{<:Species})` and `_add_agents(max_id, count::Int, species::Type{<:AnimalSpecies}, sex::Sex)` that return an array of `count` agents of species `species` with `id` going from `max_id+1` to `max_id+count`. Default parameters should be constructed with `default_config`. Make sure you can handle even animals with random sex (`@add 3 Wolf`).
+3. Define the underlying function `_ecosystem(ex)`, which parses the block expression and creates a piece of code that constructs the world.
+
+You can test the macro (more precisely the `_ecosystem` function) with the following expression
+```julia
+ex = :(begin
+    @add 10 Sheep female
+    @add 2 Sheep male
+    @add 100 Grass
+    @add 3 Wolf
+end)
+genex = _ecosystem(ex)
+world = eval(genex)
+```
+
+```@raw html
+</div></div>
+<details class = "solution-body" hidden>
+<summary class = "solution-header">Solution:</summary><p>
+```
+
+Nothing to see here
+
+```@raw html
+</p></details>
+```