Move info.toml to rustlings-macros/

This improves the experience for contributors on Windows becuase
Windows can't deal with git symbolic links out of the box…

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-format_version = 1
-
-welcome_message = """Is this your first time? Don't worry, Rustlings is made for beginners!
-We are going to teach you a lot of things about Rust, but before we can
-get started, here are some notes about how Rustlings operates:
-
-1. The central concept behind Rustlings is that you solve exercises. These
-   exercises usually contain some compiler or logic errors which cause the
-   exercise to fail compilation or testing. It's your job to find all errors
-   and fix them!
-2. Make sure to have your editor open in the `rustlings/` directory. Rustlings
-   will show you the path of the current exercise under the progress bar. Open
-   the exercise file in your editor, fix errors and save the file. Rustlings will
-   automatically detect the file change and rerun the exercise. If all errors are
-   fixed, Rustlings will ask you to move on to the next exercise.
-3. If you're stuck on an exercise, enter `h` (or `hint`) to show a hint.
-4. If an exercise doesn't make sense to you, feel free to open an issue on GitHub!
-   (https://github.com/rust-lang/rustlings). We look at every issue, and sometimes,
-   other learners do too so you can help each other out!
-"""
-
-final_message = """We hope you enjoyed learning about the various aspects of Rust!
-If you noticed any issues, don't hesitate to report them on Github.
-You can also contribute your own exercises to help the greater community!
-
-Before reporting an issue or contributing, please read our guidelines:
-https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md
-"""
-
-# INTRO
-
-# TODO: Update exercise
-[[exercises]]
-name = "intro1"
-dir = "00_intro"
-test = false
-# TODO: Fix hint
-hint = """Enter `n` (or `next`) followed by ENTER to move on to the next exercise"""
-
-[[exercises]]
-name = "intro2"
-dir = "00_intro"
-test = false
-hint = """
-The compiler is informing us that we've got the name of the print macro wrong, and has suggested an alternative."""
-
-# VARIABLES
-
-[[exercises]]
-name = "variables1"
-dir = "01_variables"
-test = false
-hint = """
-The declaration in the first line in the main function is missing a keyword
-that is needed in Rust to create a new variable binding."""
-
-[[exercises]]
-name = "variables2"
-dir = "01_variables"
-test = false
-hint = """
-The compiler message is saying that Rust cannot infer the type that the
-variable binding `x` has with what is given here.
-
-What happens if you annotate the first line in the main function with a type
-annotation?
-
-What if you give `x` a value?
-
-What if you do both?
-
-What type should `x` be, anyway?
-
-What if `x` is the same type as `10`? What if it's a different type?"""
-
-[[exercises]]
-name = "variables3"
-dir = "01_variables"
-test = false
-hint = """
-Oops! In this exercise, we have a variable binding that we've created on in the
-first line in the `main` function, and we're trying to use it in the next line,
-but we haven't given it a value.
-
-We can't print out something that isn't there; try giving `x` a value!
-
-This is an error that can cause bugs that's very easy to make in any
-programming language -- thankfully the Rust compiler has caught this for us!"""
-
-[[exercises]]
-name = "variables4"
-dir = "01_variables"
-test = false
-hint = """
-In Rust, variable bindings are immutable by default. But here we're trying
-to reassign a different value to `x`! There's a keyword we can use to make
-a variable binding mutable instead."""
-
-[[exercises]]
-name = "variables5"
-dir = "01_variables"
-test = false
-hint = """
-In `variables4` we already learned how to make an immutable variable mutable
-using a special keyword. Unfortunately this doesn't help us much in this
-exercise because we want to assign a different typed value to an existing
-variable. Sometimes you may also like to reuse existing variable names because
-you are just converting values to different types like in this exercise.
-
-Fortunately Rust has a powerful solution to this problem: 'Shadowing'!
-You can read more about 'Shadowing' in the book's section 'Variables and
-Mutability':
-https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#shadowing
-
-Try to solve this exercise afterwards using this technique."""
-
-[[exercises]]
-name = "variables6"
-dir = "01_variables"
-test = false
-hint = """
-We know about variables and mutability, but there is another important type of
-variable available: constants.
-
-Constants are always immutable and they are declared with keyword `const` rather
-than keyword `let`.
-
-Constants types must also always be annotated.
-
-Read more about constants and the differences between variables and constants
-under 'Constants' in the book's section 'Variables and Mutability':
-https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#constants
-"""
-
-# FUNCTIONS
-
-[[exercises]]
-name = "functions1"
-dir = "02_functions"
-test = false
-hint = """
-This main function is calling a function that it expects to exist, but the
-function doesn't exist. It expects this function to have the name `call_me`.
-It expects this function to not take any arguments and not return a value.
-Sounds a lot like `main`, doesn't it?"""
-
-[[exercises]]
-name = "functions2"
-dir = "02_functions"
-test = false
-hint = """
-Rust requires that all parts of a function's signature have type annotations,
-but `call_me` is missing the type annotation of `num`."""
-
-[[exercises]]
-name = "functions3"
-dir = "02_functions"
-test = false
-hint = """
-This time, the function *declaration* is okay, but there's something wrong
-with the place where we're calling the function."""
-
-[[exercises]]
-name = "functions4"
-dir = "02_functions"
-test = false
-hint = """
-The error message points to the function `sale_price` and says it expects a type
-after the `->`. This is where the function's return type should be -- take a
-look at the `is_even` function for an example!"""
-
-[[exercises]]
-name = "functions5"
-dir = "02_functions"
-test = false
-hint = """
-This is a really common error that can be fixed by removing one character.
-It happens because Rust distinguishes between expressions and statements:
-expressions return a value based on their operand(s), and statements simply
-return a `()` type which behaves just like `void` in C/C++ language.
-
-We want to return a value of `i32` type from the `square` function, but it is
-returning a `()` type...
-
-They are not the same. There are two solutions:
-1. Add a `return` ahead of `num * num;`
-2. remove `;`, make it to be `num * num`"""
-
-# IF
-
-[[exercises]]
-name = "if1"
-dir = "03_if"
-hint = """
-It's possible to do this in one line if you would like!
-
-Some similar examples from other languages:
-- In C(++) this would be: `a > b ? a : b`
-- In Python this would be:  `a if a > b else b`
-
-Remember in Rust that:
-- the `if` condition does not need to be surrounded by parentheses
-- `if`/`else` conditionals are expressions
-- Each condition is followed by a `{}` block."""
-
-[[exercises]]
-name = "if2"
-dir = "03_if"
-hint = """
-For that first compiler error, it's important in Rust that each conditional
-block returns the same type! To get the tests passing, you will need a couple
-conditions checking different input values."""
-
-[[exercises]]
-name = "if3"
-dir = "03_if"
-hint = """
-In Rust, every arm of an `if` expression has to return the same type of value.
-Make sure the type is consistent across all arms."""
-
-# QUIZ 1
-
-[[exercises]]
-name = "quiz1"
-dir = "quizzes"
-hint = "No hints this time ;)"
-
-# PRIMITIVE TYPES
-
-[[exercises]]
-name = "primitive_types1"
-dir = "04_primitive_types"
-test = false
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "primitive_types2"
-dir = "04_primitive_types"
-test = false
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "primitive_types3"
-dir = "04_primitive_types"
-test = false
-hint = """
-There's a shorthand to initialize Arrays with a certain size that does not
-require you to type in 100 items (but you certainly can if you want!).
-
-For example, you can do:
-```
-let array = ["Are we there yet?"; 10];
-```
-
-Bonus: what are some other things you could have that would return `true`
-for `a.len() >= 100`?"""
-
-[[exercises]]
-name = "primitive_types4"
-dir = "04_primitive_types"
-hint = """
-Take a look at the 'Understanding Ownership -> Slices -> Other Slices' section
-of the book: https://doc.rust-lang.org/book/ch04-03-slices.html and use the
-starting and ending (plus one) indices of the items in the `Array` that you
-want to end up in the slice.
-
-If you're curious why the first argument of `assert_eq!` does not have an
-ampersand for a reference since the second argument is a reference, take a look
-at the coercion chapter of the nomicon:
-https://doc.rust-lang.org/nomicon/coercions.html"""
-
-[[exercises]]
-name = "primitive_types5"
-dir = "04_primitive_types"
-test = false
-hint = """
-Take a look at the 'Data Types -> The Tuple Type' section of the book:
-https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
-Particularly the part about destructuring (second to last example in the
-section).
-
-You'll need to make a pattern to bind `name` and `age` to the appropriate parts
-of the tuple. You can do it!!"""
-
-[[exercises]]
-name = "primitive_types6"
-dir = "04_primitive_types"
-hint = """
-While you could use a destructuring `let` for the tuple here, try
-indexing into it instead, as explained in the last example of the
-'Data Types -> The Tuple Type' section of the book:
-https://doc.rust-lang.org/book/ch03-02-data-types.html#the-tuple-type
-Now you have another tool in your toolbox!"""
-
-# VECS
-
-[[exercises]]
-name = "vecs1"
-dir = "05_vecs"
-hint = """
-In Rust, there are two ways to define a Vector.
-1. One way is to use the `Vec::new()` function to create a new vector
-   and fill it with the `push()` method.
-2. The second way, which is simpler is to use the `vec![]` macro and
-   define your elements inside the square brackets.
-
-Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
-of the Rust book to learn more.
-"""
-
-[[exercises]]
-name = "vecs2"
-dir = "05_vecs"
-hint = """
-In the first function we are looping over the Vector and getting a reference to
-one `element` at a time.
-
-To modify the value of that `element` we need to use the `*` dereference
-operator. You can learn more in this chapter of the Rust book:
-https://doc.rust-lang.org/stable/book/ch08-01-vectors.html#iterating-over-the-values-in-a-vector
-
-In the second function this dereferencing is not necessary, because the `map`
-function expects the new value to be returned.
-
-After you've completed both functions, decide for yourself which approach you
-like better.
-
-What do you think is the more commonly used pattern under Rust developers?
-"""
-
-# MOVE SEMANTICS
-
-[[exercises]]
-name = "move_semantics1"
-dir = "06_move_semantics"
-hint = """
-So you've got the "cannot borrow immutable local variable `vec` as mutable"
-error on the line where we push an element to the vector, right?
-
-The fix for this is going to be adding one keyword, and the addition is NOT on
-the line where we push to the vector (where the error is).
-
-Also: Try accessing `vec0` after having called `fill_vec()`. See what
-happens!"""
-
-[[exercises]]
-name = "move_semantics2"
-dir = "06_move_semantics"
-hint = """
-When running this exercise for the first time, you'll notice an error about
-"borrow of moved value". In Rust, when an argument is passed to a function and
-it's not explicitly returned, you can't use the original variable anymore.
-We call this "moving" a variable. When we pass `vec0` into `fill_vec`, it's
-being "moved" into `vec1`, meaning we can't access `vec0` anymore after the
-fact.
-
-Rust provides a couple of different ways to mitigate this issue, feel free to
-try them all:
-1. You could make another, separate version of the data that's in `vec0` and
-   pass that to `fill_vec` instead.
-2. Make `fill_vec` borrow its argument instead of taking ownership of it,
-   and then copy the data within the function (`vec.clone()`) in order to
-   return an owned `Vec<i32>`.
-"""
-
-[[exercises]]
-name = "move_semantics3"
-dir = "06_move_semantics"
-hint = """
-The difference between this one and the previous ones is that the first line
-of `fn fill_vec` that had `let mut vec = vec;` is no longer there. You can,
-instead of adding that line back, add `mut` in one place that will change
-an existing binding to be a mutable binding instead of an immutable one :)"""
-
-[[exercises]]
-name = "move_semantics4"
-dir = "06_move_semantics"
-hint = """
-Stop reading whenever you feel like you have enough direction :) Or try
-doing one step and then fixing the compiler errors that result!
-So the end goal is to:
-   - get rid of the first line in main that creates the new vector
-   - so then `vec0` doesn't exist, so we can't pass it to `fill_vec`
-   - `fill_vec` has had its signature changed, which our call should reflect
-   - since we're not creating a new vec in `main` anymore, we need to create
-     a new vec in `fill_vec`, and fill it with the expected values"""
-
-[[exercises]]
-name = "move_semantics5"
-dir = "06_move_semantics"
-hint = """
-Carefully reason about the range in which each mutable reference is in
-scope. Does it help to update the value of referent (`x`) immediately after
-the mutable reference is taken? Read more about 'Mutable References'
-in the book's section 'References and Borrowing':
-https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#mutable-references.
-"""
-
-[[exercises]]
-name = "move_semantics6"
-dir = "06_move_semantics"
-test = false
-hint = """
-To find the answer, you can consult the book section "References and Borrowing":
-https://doc.rust-lang.org/stable/book/ch04-02-references-and-borrowing.html
-
-The first problem is that `get_char` is taking ownership of the string. So
-`data` is moved and can't be used for `string_uppercase`. `data` is moved to
-`get_char` first, meaning that `string_uppercase` cannot manipulate the data.
-
-Once you've fixed that, `string_uppercase`'s function signature will also need
-to be adjusted.
-
-Can you figure out how?
-
-Another hint: it has to do with the `&` character."""
-
-# STRUCTS
-
-[[exercises]]
-name = "structs1"
-dir = "07_structs"
-hint = """
-Rust has more than one type of struct. Three actually, all variants are used to
-package related data together.
-
-There are normal (or classic) structs. These are named collections of related
-data stored in fields.
-
-Tuple structs are basically just named tuples.
-
-Finally, Unit-like structs. These don't have any fields and are useful for
-generics.
-
-In this exercise you need to complete and implement one of each kind.
-Read more about structs in The Book:
-https://doc.rust-lang.org/book/ch05-01-defining-structs.html"""
-
-[[exercises]]
-name = "structs2"
-dir = "07_structs"
-hint = """
-Creating instances of structs is easy, all you need to do is assign some values
-to its fields.
-
-There are however some shortcuts that can be taken when instantiating structs.
-Have a look in The Book, to find out more:
-https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax"""
-
-[[exercises]]
-name = "structs3"
-dir = "07_structs"
-hint = """
-For `is_international`: What makes a package international? Seems related to
-the places it goes through right?
-
-For `get_fees`: This method takes an additional argument, is there a field in
-the `Package` struct that this relates to?
-
-Have a look in The Book, to find out more about method implementations:
-https://doc.rust-lang.org/book/ch05-03-method-syntax.html"""
-
-# ENUMS
-
-[[exercises]]
-name = "enums1"
-dir = "08_enums"
-test = false
-hint = "No hints this time ;)"
-
-[[exercises]]
-name = "enums2"
-dir = "08_enums"
-test = false
-hint = """
-You can create enumerations that have different variants with different types
-such as no data, anonymous structs, a single string, tuples, ...etc"""
-
-[[exercises]]
-name = "enums3"
-dir = "08_enums"
-hint = """
-As a first step, you can define enums to compile this code without errors.
-
-And then create a match expression in `process()`.
-
-Note that you need to deconstruct some message variants in the match expression
-to get value in the variant."""
-
-# STRINGS
-
-[[exercises]]
-name = "strings1"
-dir = "09_strings"
-test = false
-hint = """
-The `current_favorite_color` function is currently returning a string slice
-with the `'static` lifetime. We know this because the data of the string lives
-in our code itself -- it doesn't come from a file or user input or another
-program -- so it will live as long as our program lives.
-
-But it is still a string slice. There's one way to create a `String` by
-converting a string slice covered in the Strings chapter of the book, and
-another way that uses the `From` trait."""
-
-[[exercises]]
-name = "strings2"
-dir = "09_strings"
-test = false
-hint = """
-Yes, it would be really easy to fix this by just changing the value bound to
-`word` to be a string slice instead of a `String`, wouldn't it?? There is a way
-to add one character to the `if` statement, though, that will coerce the
-`String` into a string slice.
-
-Side note: If you're interested in learning about how this kind of reference
-conversion works, you can jump ahead in the book and read this part in the
-smart pointers chapter:
-https://doc.rust-lang.org/stable/book/ch15-02-deref.html#implicit-deref-coercions-with-functions-and-methods"""
-
-[[exercises]]
-name = "strings3"
-dir = "09_strings"
-hint = """
-There's tons of useful standard library functions for strings. Let's try and use some of them:
-https://doc.rust-lang.org/std/string/struct.String.html#method.trim
-
-For the `compose_me` method: You can either use the `format!` macro, or convert
-the string slice into an owned string, which you can then freely extend."""
-
-[[exercises]]
-name = "strings4"
-dir = "09_strings"
-test = false
-hint = "No hints this time ;)"
-
-# MODULES
-
-[[exercises]]
-name = "modules1"
-dir = "10_modules"
-test = false
-hint = """
-Everything is private in Rust by default-- but there's a keyword we can use
-to make something public! The compiler error should point to the thing that
-needs to be public."""
-
-[[exercises]]
-name = "modules2"
-dir = "10_modules"
-test = false
-hint = """
-The delicious_snacks module is trying to present an external interface that is
-different than its internal structure (the `fruits` and `veggies` modules and
-associated constants). Complete the `use` statements to fit the uses in main and
-find the one keyword missing for both constants.
-
-Learn more at https://doc.rust-lang.org/book/ch07-04-bringing-paths-into-scope-with-the-use-keyword.html#re-exporting-names-with-pub-use"""
-
-[[exercises]]
-name = "modules3"
-dir = "10_modules"
-test = false
-hint = """
-`UNIX_EPOCH` and `SystemTime` are declared in the `std::time` module. Add a
-`use` statement for these two to bring them into scope. You can use nested
-paths or the glob operator to bring these two in using only one line."""
-
-# HASHMAPS
-
-[[exercises]]
-name = "hashmaps1"
-dir = "11_hashmaps"
-hint = """
-Hint 1: Take a look at the return type of the function to figure out
-        the type for the `basket`.
-
-Hint 2: Number of fruits should be at least 5. And you have to put
-        at least three different types of fruits.
-"""
-
-[[exercises]]
-name = "hashmaps2"
-dir = "11_hashmaps"
-hint = """
-Use the `entry()` and `or_insert()` methods of `HashMap` to achieve this.
-Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
-"""
-
-[[exercises]]
-name = "hashmaps3"
-dir = "11_hashmaps"
-hint = """
-Hint 1: Use the `entry()` and `or_insert()` methods of `HashMap` to insert
-        entries corresponding to each team in the scores table.
-
-Learn more at https://doc.rust-lang.org/stable/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
-
-Hint 2: If there is already an entry for a given key, the value returned by
-        `entry()` can be updated based on the existing value.
-
-Learn more at https://doc.rust-lang.org/book/ch08-03-hash-maps.html#updating-a-value-based-on-the-old-value
-"""
-
-# QUIZ 2
-
-[[exercises]]
-name = "quiz2"
-dir = "quizzes"
-hint = "No hints this time ;)"
-
-# OPTIONS
-
-[[exercises]]
-name = "options1"
-dir = "12_options"
-hint = """
-Options can have a `Some` value, with an inner value, or a `None` value,
-without an inner value.
-
-There's multiple ways to get at the inner value, you can use `unwrap`, or
-pattern match. Unwrapping is the easiest, but how do you do it safely so that
-it doesn't panic in your face later?"""
-
-[[exercises]]
-name = "options2"
-dir = "12_options"
-hint = """
-Check out:
-
-- https://doc.rust-lang.org/rust-by-example/flow_control/if_let.html
-- https://doc.rust-lang.org/rust-by-example/flow_control/while_let.html
-
-Remember that `Option`s can be stacked in `if let` and `while let`.
-
-For example: `Some(Some(variable)) = variable2`
-
-Also see `Option::flatten`
-"""
-
-[[exercises]]
-name = "options3"
-dir = "12_options"
-test = false
-hint = """
-The compiler says a partial move happened in the `match` statement. How can
-this be avoided? The compiler shows the correction needed.
-
-After making the correction as suggested by the compiler, do read:
-https://doc.rust-lang.org/std/keyword.ref.html"""
-
-# ERROR HANDLING
-
-[[exercises]]
-name = "errors1"
-dir = "13_error_handling"
-hint = """
-`Ok` and `Err` are the two variants of `Result`, so what the tests are saying
-is that `generate_nametag_text` should return a `Result` instead of an `Option`.
-
-To make this change, you'll need to:
-  - update the return type in the function signature to be a `Result<String,
-    String>` that could be the variants `Ok(String)` and `Err(String)`
-  - change the body of the function to return `Ok(stuff)` where it currently
-    returns `Some(stuff)`
-  - change the body of the function to return `Err(error message)` where it
-    currently returns `None`"""
-
-[[exercises]]
-name = "errors2"
-dir = "13_error_handling"
-hint = """
-One way to handle this is using a `match` statement on
-`item_quantity.parse::<i32>()` where the cases are `Ok(something)` and
-`Err(something)`.
-
-This pattern is very common in Rust, though, so there's a `?` operator that
-does pretty much what you would make that match statement do for you!
-
-Take a look at this section of the 'Error Handling' chapter:
-https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator
-and give it a try!"""
-
-[[exercises]]
-name = "errors3"
-dir = "13_error_handling"
-test = false
-hint = """
-If other functions can return a `Result`, why shouldn't `main`? It's a fairly
-common convention to return something like `Result<(), ErrorType>` from your
-main function.
-
-The unit (`()`) type is there because nothing is really needed in terms of
-positive results."""
-
-[[exercises]]
-name = "errors4"
-dir = "13_error_handling"
-hint = """
-`PositiveNonzeroInteger::new` is always creating a new instance and returning
-an `Ok` result.
-
-It should be doing some checking, returning an `Err` result if those checks
-fail, and only returning an `Ok` result if those checks determine that
-everything is... okay :)"""
-
-[[exercises]]
-name = "errors5"
-dir = "13_error_handling"
-test = false
-hint = """
-There are two different possible `Result` types produced within `main()`, which
-are propagated using `?` operators. How do we declare a return type from
-`main()` that allows both?
-
-Under the hood, the `?` operator calls `From::from` on the error value to
-convert it to a boxed trait object, a `Box<dyn error::Error>`. This boxed trait
-object is polymorphic, and since all errors implement the `error::Error` trait,
-we can capture lots of different errors in one "Box" object.
-
-Check out this section of the book:
-https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator
-
-Read more about boxing errors:
-https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/boxing_errors.html
-
-Read more about using the `?` operator with boxed errors:
-https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
-"""
-
-[[exercises]]
-name = "errors6"
-dir = "13_error_handling"
-hint = """
-This exercise uses a completed version of `PositiveNonzeroInteger` from
-errors4.
-
-Below the line that `TODO` asks you to change, there is an example of using
-the `map_err()` method on a `Result` to transform one type of error into
-another. Try using something similar on the `Result` from `parse()`. You
-might use the `?` operator to return early from the function, or you might
-use a `match` expression, or maybe there's another way!
-
-You can create another function inside `impl ParsePosNonzeroError` to use
-with `map_err()`.
-
-Read more about `map_err()` in the `std::result` documentation:
-https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
-
-# Generics
-
-[[exercises]]
-name = "generics1"
-dir = "14_generics"
-test = false
-hint = """
-Vectors in Rust make use of generics to create dynamically sized arrays of any
-type.
-
-You need to tell the compiler what type we are pushing onto this vector."""
-
-[[exercises]]
-name = "generics2"
-dir = "14_generics"
-hint = """
-Currently we are wrapping only values of type `u32`.
-
-Maybe we could update the explicit references to this data type somehow?
-
-If you are still stuck https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions
-"""
-
-# TRAITS
-
-[[exercises]]
-name = "traits1"
-dir = "15_traits"
-hint = """
-A discussion about Traits in Rust can be found at:
-https://doc.rust-lang.org/book/ch10-02-traits.html
-"""
-
-[[exercises]]
-name = "traits2"
-dir = "15_traits"
-hint = """
-Notice how the trait takes ownership of `self`, and returns `Self`.
-
-Try mutating the incoming string vector. Have a look at the tests to see
-what the result should look like!
-
-Vectors provide suitable methods for adding an element at the end. See
-the documentation at: https://doc.rust-lang.org/std/vec/struct.Vec.html"""
-
-[[exercises]]
-name = "traits3"
-dir = "15_traits"
-hint = """
-Traits can have a default implementation for functions. Structs that implement
-the trait can then use the default version of these functions if they choose not
-to implement the function themselves.
-
-See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#default-implementations
-"""
-
-[[exercises]]
-name = "traits4"
-dir = "15_traits"
-hint = """
-Instead of using concrete types as parameters you can use traits. Try replacing
-the '??' with 'impl <what goes here?>'
-
-See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters
-"""
-
-[[exercises]]
-name = "traits5"
-dir = "15_traits"
-test = false
-hint = """
-To ensure a parameter implements multiple traits use the '+ syntax'. Try
-replacing the '??' with 'impl <> + <>'.
-
-See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#specifying-multiple-trait-bounds-with-the--syntax
-"""
-
-# QUIZ 3
-
-[[exercises]]
-name = "quiz3"
-dir = "quizzes"
-hint = """
-To find the best solution to this challenge you're going to need to think back
-to your knowledge of traits, specifically 'Trait Bound Syntax'
-
-You may also need this: `use std::fmt::Display;`."""
-
-# LIFETIMES
-
-[[exercises]]
-name = "lifetimes1"
-dir = "16_lifetimes"
-test = false
-hint = """
-Let the compiler guide you. Also take a look at the book if you need help:
-https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html"""
-
-[[exercises]]
-name = "lifetimes2"
-dir = "16_lifetimes"
-test = false
-hint = """
-Remember that the generic lifetime `'a` will get the concrete lifetime that is
-equal to the smaller of the lifetimes of `x` and `y`.
-
-You can take at least two paths to achieve the desired result while keeping the
-inner block:
-1. Move the `string2` declaration to make it live as long as `string1` (how is
-   `result` declared?)
-2. Move `println!` into the inner block"""
-
-[[exercises]]
-name = "lifetimes3"
-dir = "16_lifetimes"
-test = false
-hint = """
-If you use a lifetime annotation in a struct's fields, where else does it need
-to be added?"""
-
-# TESTS
-
-[[exercises]]
-name = "tests1"
-dir = "17_tests"
-hint = """
-You don't even need to write any code to test -- you can just test values and
-run that, even though you wouldn't do that in real life. :)
-
-`assert!` is a macro that needs an argument. Depending on the value of the
-argument, `assert!` will do nothing (in which case the test will pass) or
-`assert!` will panic (in which case the test will fail).
-
-So try giving different values to `assert!` and see which ones compile, which
-ones pass, and which ones fail :)"""
-
-[[exercises]]
-name = "tests2"
-dir = "17_tests"
-hint = """
-Like the previous exercise, you don't need to write any code to get this test
-to compile and run.
-
-`assert_eq!` is a macro that takes two arguments and compares them. Try giving
-it two values that are equal! Try giving it two arguments that are different!
-Try giving it two values that are of different types! Try switching which
-argument comes first and which comes second!"""
-
-[[exercises]]
-name = "tests3"
-dir = "17_tests"
-hint = """
-You can call a function right where you're passing arguments to `assert!`. So
-you could do something like `assert!(having_fun())`.
-
-If you want to check that you indeed get `false`, you can negate the result of
-what you're doing using `!`, like `assert!(!having_fun())`."""
-
-[[exercises]]
-name = "tests4"
-dir = "17_tests"
-hint = """
-We expect method `Rectangle::new()` to panic for negative values.
-
-To handle that you need to add a special attribute to the test function.
-
-You can refer to the docs:
-https://doc.rust-lang.org/stable/book/ch11-01-writing-tests.html#checking-for-panics-with-should_panic"""
-
-# STANDARD LIBRARY TYPES
-
-[[exercises]]
-name = "iterators1"
-dir = "18_iterators"
-hint = """
-Step 1:
-
-We need to apply something to the collection `my_fav_fruits` before we start to
-go through it. What could that be? Take a look at the struct definition for a
-vector for inspiration:
-https://doc.rust-lang.org/std/vec/struct.Vec.html
-
-Step 2 & step 3:
-
-Very similar to the lines above and below. You've got this!
-
-Step 4:
-
-An iterator goes through all elements in a collection, but what if we've run
-out of elements? What should we expect here? If you're stuck, take a look at
-https://doc.rust-lang.org/std/iter/trait.Iterator.html for some ideas.
-"""
-
-[[exercises]]
-name = "iterators2"
-dir = "18_iterators"
-hint = """
-Step 1:
-
-The variable `first` is a `char`. It needs to be capitalized and added to the
-remaining characters in `c` in order to return the correct `String`.
-
-The remaining characters in `c` can be viewed as a string slice using the
-`as_str` method.
-
-The documentation for `char` contains many useful methods.
-https://doc.rust-lang.org/std/primitive.char.html
-
-Step 2:
-
-Create an iterator from the slice. Transform the iterated values by applying
-the `capitalize_first` function. Remember to `collect` the iterator.
-
-Step 3:
-
-This is surprisingly similar to the previous solution. `collect` is very
-powerful and very general. Rust just needs to know the desired type."""
-
-[[exercises]]
-name = "iterators3"
-dir = "18_iterators"
-hint = """
-The `divide` function needs to return the correct error when even division is
-not possible.
-
-The `division_results` variable needs to be collected into a collection type.
-
-The `result_with_list` function needs to return a single `Result` where the
-success case is a vector of integers and the failure case is a `DivisionError`.
-
-The `list_of_results` function needs to return a vector of results.
-
-See https://doc.rust-lang.org/std/iter/trait.Iterator.html#method.collect for
-how the `FromIterator` trait is used in `collect()`. This trait is REALLY
-powerful! It can make the solution to this exercise infinitely easier."""
-
-[[exercises]]
-name = "iterators4"
-dir = "18_iterators"
-hint = """
-In an imperative language, you might write a `for` loop that updates a mutable
-variable. Or, you might write code utilizing recursion and a match clause. In
-Rust you can take another functional approach, computing the factorial
-elegantly with ranges and iterators.
-
-Hint 2: Check out the `fold` and `rfold` methods!"""
-
-[[exercises]]
-name = "iterators5"
-dir = "18_iterators"
-hint = """
-The documentation for the `std::iter::Iterator` trait contains numerous methods
-that would be helpful here.
-
-The `collection` variable in `count_collection_iterator` is a slice of
-`HashMap`s. It needs to be converted into an iterator in order to use the
-iterator methods.
-
-The `fold` method can be useful in the `count_collection_iterator` function.
-
-For a further challenge, consult the documentation for `Iterator` to find
-a different method that could make your code more compact than using `fold`."""
-
-# SMART POINTERS
-
-[[exercises]]
-name = "box1"
-dir = "19_smart_pointers"
-hint = """
-Step 1:
-
-The compiler's message should help: since we cannot store the value of the
-actual type when working with recursive types, we need to store a reference
-(pointer) to its value.
-
-We should, therefore, place our `List` inside a `Box`. More details in the book
-here: https://doc.rust-lang.org/book/ch15-01-box.html#enabling-recursive-types-with-boxes
-
-Step 2:
-
-Creating an empty list should be fairly straightforward (hint: peek at the
-assertions).
-
-For a non-empty list keep in mind that we want to use our `Cons` "list builder".
-Although the current list is one of integers (`i32`), feel free to change the
-definition and try other types!
-"""
-
-[[exercises]]
-name = "rc1"
-dir = "19_smart_pointers"
-hint = """
-This is a straightforward exercise to use the `Rc<T>` type. Each `Planet` has
-ownership of the `Sun`, and uses `Rc::clone()` to increment the reference count
-of the `Sun`.
-
-After using `drop()` to move the `Planet`s out of scope individually, the
-reference count goes down.
-
-In the end the `Sun` only has one reference again, to itself.
-
-See more at: https://doc.rust-lang.org/book/ch15-04-rc.html
-
-* Unfortunately Pluto is no longer considered a planet :(
-"""
-
-[[exercises]]
-name = "arc1"
-dir = "19_smart_pointers"
-test = false
-hint = """
-Make `shared_numbers` be an `Arc` from the numbers vector. Then, in order
-to avoid creating a copy of `numbers`, you'll need to create `child_numbers`
-inside the loop but still in the main thread.
-
-`child_numbers` should be a clone of the `Arc` of the numbers instead of a
-thread-local copy of the numbers.
-
-This is a simple exercise if you understand the underlying concepts, but if this
-is too much of a struggle, consider reading through all of Chapter 16 in the
-book:
-https://doc.rust-lang.org/stable/book/ch16-00-concurrency.html
-"""
-
-[[exercises]]
-name = "cow1"
-dir = "19_smart_pointers"
-hint = """
-If `Cow` already owns the data it doesn't need to clone it when `to_mut()` is
-called.
-
-Check out https://doc.rust-lang.org/std/borrow/enum.Cow.html for documentation
-on the `Cow` type.
-"""
-
-# THREADS
-
-[[exercises]]
-name = "threads1"
-dir = "20_threads"
-test = false
-hint = """
-`JoinHandle` is a struct that is returned from a spawned thread:
-https://doc.rust-lang.org/std/thread/fn.spawn.html
-
-A challenge with multi-threaded applications is that the main thread can
-finish before the spawned threads are completed.
-https://doc.rust-lang.org/book/ch16-01-threads.html#waiting-for-all-threads-to-finish-using-join-handles
-
-Use the `JoinHandle`s to wait for each thread to finish and collect their
-results.
-
-https://doc.rust-lang.org/std/thread/struct.JoinHandle.html
-"""
-
-[[exercises]]
-name = "threads2"
-dir = "20_threads"
-test = false
-hint = """
-`Arc` is an Atomic Reference Counted pointer that allows safe, shared access
-to **immutable** data. But we want to *change* the number of `jobs_completed`
-so we'll need to also use another type that will only allow one thread to
-mutate the data at a time. Take a look at this section of the book:
-https://doc.rust-lang.org/book/ch16-03-shared-state.html#atomic-reference-counting-with-arct
-
-Keep reading if you'd like more hints :)
-
-Do you now have an `Arc<Mutex<JobStatus>>` at the beginning of `main`? Like:
-```
-let status = Arc::new(Mutex::new(JobStatus { jobs_completed: 0 }));
-```
-
-Similar to the code in the following example in the book:
-https://doc.rust-lang.org/book/ch16-03-shared-state.html#sharing-a-mutext-between-multiple-threads
-"""
-
-[[exercises]]
-name = "threads3"
-dir = "20_threads"
-hint = """
-An alternate way to handle concurrency between threads is to use an `mpsc`
-(multiple producer, single consumer) channel to communicate.
-
-With both a sending end and a receiving end, it's possible to send values in
-one thread and receive them in another.
-
-Multiple producers are possible by using clone() to create a duplicate of the
-original sending end.
-
-See https://doc.rust-lang.org/book/ch16-02-message-passing.html for more info.
-"""
-
-# MACROS
-
-[[exercises]]
-name = "macros1"
-dir = "21_macros"
-test = false
-hint = """
-When you call a macro, you need to add something special compared to a
-regular function call. If you're stuck, take a look at what's inside
-`my_macro`."""
-
-[[exercises]]
-name = "macros2"
-dir = "21_macros"
-test = false
-hint = """
-Macros don't quite play by the same rules as the rest of Rust, in terms of
-what's available where.
-
-Unlike other things in Rust, the order of "where you define a macro" versus
-"where you use it" actually matters."""
-
-[[exercises]]
-name = "macros3"
-dir = "21_macros"
-test = false
-hint = """
-In order to use a macro outside of its module, you need to do something
-special to the module to lift the macro out into its parent.
-
-The same trick also works on "extern crate" statements for crates that have
-exported macros, if you've seen any of those around."""
-
-[[exercises]]
-name = "macros4"
-dir = "21_macros"
-test = false
-hint = """
-You only need to add a single character to make this compile.
-
-The way macros are written, it wants to see something between each "macro arm",
-so it can separate them.
-
-That's all the macro exercises we have in here, but it's barely even scratching
-the surface of what you can do with Rust's macros. For a more thorough
-introduction, you can have a read through 'The Little Book of Rust Macros':
-https://veykril.github.io/tlborm/"""
-
-#  CLIPPY
-
-[[exercises]]
-name = "clippy1"
-dir = "22_clippy"
-test = false
-strict_clippy = true
-hint = """
-Rust stores the highest precision version of any long or infinite precision
-mathematical constants in the Rust standard library:
-https://doc.rust-lang.org/stable/std/f32/consts/index.html
-
-We may be tempted to use our own approximations for certain mathematical
-constants, but clippy recognizes those imprecise mathematical constants as a
-source of potential error.
-
-See the suggestions of the clippy warning in compile output and use the
-appropriate replacement constant from `std::f32::consts`..."""
-
-[[exercises]]
-name = "clippy2"
-dir = "22_clippy"
-test = false
-strict_clippy = true
-hint = """
-`for` loops over `Option` values are more clearly expressed as an `if let`"""
-
-[[exercises]]
-name = "clippy3"
-dir = "22_clippy"
-test = false
-strict_clippy = true
-hint = "No hints this time!"
-
-# TYPE CONVERSIONS
-
-[[exercises]]
-name = "using_as"
-dir = "23_conversions"
-hint = """
-Use the `as` operator to cast one of the operands in the last line of the
-`average` function into the expected return type."""
-
-[[exercises]]
-name = "from_into"
-dir = "23_conversions"
-hint = """
-Follow the steps provided right before the `From` implementation"""
-
-[[exercises]]
-name = "from_str"
-dir = "23_conversions"
-hint = """
-The implementation of `FromStr` should return an `Ok` with a `Person` object,
-or an `Err` with an error if the string is not valid.
-
-This is almost like the `from_into` exercise, but returning errors instead
-of falling back to a default value.
-
-Look at the test cases to see which error variants to return.
-
-Another hint: You can use the `map_err` method of `Result` with a function
-or a closure to wrap the error from `parse::<usize>`.
-
-Yet another hint: If you would like to propagate errors by using the `?`
-operator in your solution, you might want to look at
-https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
-"""
-
-[[exercises]]
-name = "try_from_into"
-dir = "23_conversions"
-hint = """
-Follow the steps provided right before the `TryFrom` implementation.
-You can also use the example at
-https://doc.rust-lang.org/std/convert/trait.TryFrom.html
-
-Is there an implementation of `TryFrom` in the standard library that
-can both do the required integer conversion and check the range of the input?
-
-Another hint: Look at the test cases to see which error variants to return.
-
-Yet another hint: You can use the `map_err` or `or` methods of `Result` to
-convert errors.
-
-Yet another hint: If you would like to propagate errors by using the `?`
-operator in your solution, you might want to look at
-https://doc.rust-lang.org/stable/rust-by-example/error/multiple_error_types/reenter_question_mark.html
-
-Challenge: Can you make the `TryFrom` implementations generic over many integer types?"""
-
-[[exercises]]
-name = "as_ref_mut"
-dir = "23_conversions"
-hint = """
-Add `AsRef<str>` or `AsMut<u32>` as a trait bound to the functions."""