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diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml new file mode 100644 index 0000000..8b72046 --- /dev/null +++ b/rustlings-macros/info.toml @@ -0,0 +1,1200 @@ +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` 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 + +[[exercises]] +name = "intro1" +dir = "00_intro" +test = false +skip_check_unsolved = true +hint = """ +Enter `n` to move on to the next exercise. +You might need to press ENTER after typing `n`.""" + +[[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. +It also suggests an alternative.""" + +# VARIABLES + +[[exercises]] +name = "variables1" +dir = "01_variables" +test = false +hint = """ +The declaration 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 can't 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 = """ +In this exercise, we have a variable binding that we've created 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 +variables available: constants. + +Constants are always immutable. They are declared with the keyword `const` instead +of `let`. + +The type of Constants must 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 also 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 are 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 `->`. 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++. + +We want to return a value with the type `i32` from the `square` function, but +it is returning the type `()`. + +There are two solutions: +1. Add the `return` keyword before `num * num;` +2. Remove the semicolon `;` after `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. Read the tests to find out what they expect.""" + +[[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 = """ +In Rust, a boolean can be negated using the operator `!` before it. +Example: `!true == false` +This also works with boolean variables.""" + +[[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 doesn't +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.""" + +[[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 is to use the `vec![]` macro and define your elements + inside the square brackets. This way is simpler when you exactly know + the initial values. + +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 create an empty vector and want to push new elements +to it. + +In the second function, we map the values of the input and collect them into a vector. + +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 `vec` as mutable, as it is not declared 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). + +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. + +You could make another, separate version of the data that's in `vec0` and +pass it to `fill_vec` instead.""" + +[[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 = """ +Carefully reason about the range in which each mutable reference is in +scope. Does it help to update the value of `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_semantics5" +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` can't manipulate the data. + +Once you've fixed that, `string_uppercase`'s function signature will also need +to be adjusted.""" + +# 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 regular structs. These are named collections of related data stored in +fields. + +Tuple structs are basically just named tuples. + +Finally, unit 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 anonymous structs, a single string, tuples, no data, etc.""" + +[[exercises]] +name = "enums3" +dir = "08_enums" +hint = """ +As a first step, define enums to compile the code without errors. + +Then, create a match expression in `process()`. + +Note that you need to deconstruct some message variants in the match expression +to get the variant's values.""" + +# 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 are many 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 = """ +Replace `placeholder` with either `string` or `string_slice` in the `main` function. + +Example: +`placeholder("blue");` +should become +`string_slice("blue");` +because "blue" is `&str`, not `String`.""" + +# 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!""" + +[[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 in The Book: +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 to bring these two in using only one line.""" + +# HASHMAPS + +[[exercises]] +name = "hashmaps1" +dir = "11_hashmaps" +hint = """ +The number of fruits should be at least 5 and you have to put at least 3 +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 in The Book: +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()` (or `or_insert_with()`) methods of + `HashMap` to insert the default value of `Team` if a team doesn't + exist in the table yet. + +Learn more in The Book: +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 in The Book: +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 are 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 nested in if-let and while-let statements. + +For example: `if let Some(Some(x)) = y` + +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, read the related docs +page: +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(…)` where it currently + returns `Some(…)` + - 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 the `?` 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""" + +[[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 a +positive result.""" + +[[exercises]] +name = "errors4" +dir = "13_error_handling" +hint = """ +`PositiveNonzeroInteger::new` is always creating a new instance and returning +an `Ok` result. But it should be doing some checking, returning an `Err` if +those checks fail, and only returning an `Ok` 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 the `main` +function, which are propagated using the `?` operators. How do we declare a +return type for the `main` function 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>`. This boxed trait object +is polymorphic, and since all errors implement the `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 the +previous exercises. + +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 +can then use the `?` operator to return early. + +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. +If the vector `numbers` has the type `Vec<T>`, then we can only push values of +type `T` to it. By using `into()` before pushing, we ask the compiler to convert +`n1` and `n2` to `T`. But the compiler doesn't know what `T` is yet and needs a +type annotation. + +`u8` and `i8` can both be converted to `i16`, `i32` and `i64`. Choose one for +the generic of the vector.""" + +[[exercises]] +name = "generics2" +dir = "14_generics" +hint = """ +Related section in The Book: +https://doc.rust-lang.org/stable/book/ch10-01-syntax.html#in-method-definitions""" + +# TRAITS + +[[exercises]] +name = "traits1" +dir = "15_traits" +hint = """ +More about traits in The Book: +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`. + +Although the signature of `append_bar` in the trait takes `self` as argument, +the implementation can take `mut self` instead. This is possible because the +the value is owned anyway.""" + +[[exercises]] +name = "traits3" +dir = "15_traits" +hint = """ +Traits can have a default implementation for functions. Data types that +implement the trait can then use the default version of these functions +if they choose not to implement the function themselves. + +Related section in The Book: +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 +`???` with `impl [what goes here?]`. + +Related section in The Book: +https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters""" + +[[exercises]] +name = "traits5" +dir = "15_traits" +hint = """ +To ensure a parameter implements multiple traits use the '+ syntax'. Try +replacing `???` with 'impl [what goes here?] + [what goes here?]'. + +Related section in The Book: +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 need to recall your knowledge +of traits, specifically "Trait Bound Syntax": +https://doc.rust-lang.org/book/ch10-02-traits.html#trait-bound-syntax + +Here is how to specify a trait bound for an implementation block: +`impl<T: Trait1 + Trait2 + …> for Foo<T> { … }` + +You may need this: +`use std::fmt::Display;`""" + +# LIFETIMES + +[[exercises]] +name = "lifetimes1" +dir = "16_lifetimes" +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 = """Let the compiler guide you :)""" + +# TESTS + +[[exercises]] +name = "tests1" +dir = "17_tests" +hint = """ +`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 :) + +If you want to check for `false`, you can negate the result of what you're +checking using `!`, like `assert!(!…)`.""" + +[[exercises]] +name = "tests2" +dir = "17_tests" +hint = """ +`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 switching which argument comes first and which comes second!""" + +[[exercises]] +name = "tests3" +dir = "17_tests" +hint = """ +We expect the 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 = """ +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""" + +[[exercises]] +name = "iterators2" +dir = "18_iterators" +hint = """ +`capitalize_first`: + +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 + +Use `char::to_uppercase`. It returns an iterator that can be converted to a +`String`. + +`capitalize_words_vector`: + +Create an iterator from the slice. Transform the iterated values by applying +the `capitalize_first` function. Remember to `collect` the iterator. + +`capitalize_words_string`: + +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 the divisor is 0 or +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 much 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. + +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 = """ +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: +https://doc.rust-lang.org/book/ch15-01-box.html#enabling-recursive-types-with-boxes + +Creating an empty list should be fairly straightforward (Hint: Read the tests). + +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 the documentation of the `Cow` type: +https://doc.rust-lang.org/std/borrow/enum.Cow.html""" + +# 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 done. +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_done` 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_done: 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. + +Related section in The Book: +https://doc.rust-lang.org/book/ch16-02-message-passing.html""" + +# 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.""" + +[[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.""" + +[[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 some 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 the 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` +statement.""" + +[[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 previous `from_into` exercise, but returning errors +instead of falling back to a default value. + +Another hint: You can use the `map_err` method of `Result` with a function or a +closure to wrap the error from `parse::<u8>`. + +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 = """ +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? + +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.""" |