some work on part 02, and the layout

diff --git a/Makefile b/Makefile
index 830ba375e150607e20fd9b0e9dcdbf7dffd966de..dc3ffb02c3be03f3a44fce6636e037ab20087179 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ all: docs rawsrc
 .PHONY: docs rawsrc
 
 docs:
 .PHONY: docs rawsrc
 
 docs:

-       @docco $(FILES) -l linear
+       @docco $(FILES) # -l linear

 
 rawsrc:
        @mkdir -p rawsrc
 
 rawsrc:
        @mkdir -p rawsrc

diff --git a/src/main.rs b/src/main.rs
index 7850a99e2dd80dd13822445a006179ca203d9eee..fdc8f5fe56fca1bb607b8daf9d65ea371854ce47 100644 (file)
--- a/src/main.rs
+++ b/src/main.rs
@@ -42,13 +42,13 @@
 // * [Part 01](part01.html)
 // * [Part 02](part02.html) (WIP)
 // * (to be continued)
 // * [Part 01](part01.html)
 // * [Part 02](part02.html) (WIP)
 // * (to be continued)

-#![allow(dead_code)]
+#![allow(dead_code, unused_imports, unused_variables)]

 mod part00;
 mod part01;
 mod part02;
 
 // To actually run the code of some part (after filling in the blanks, if necessary), simply edit the `main`
 mod part00;
 mod part01;
 mod part02;
 
 // To actually run the code of some part (after filling in the blanks, if necessary), simply edit the `main`

-// function below.
+// function.

 
 fn main() {
     part00::part_main();
 
 fn main() {
     part00::part_main();

diff --git a/src/part00.rs b/src/part00.rs
index 7fcbf3592b87aecf710c9d517b006d353a1ebc74..90b04ef75bd6bf15d1ccc66b4cbf496c168e70ac 100644 (file)
--- a/src/part00.rs
+++ b/src/part00.rs
@@ -2,8 +2,9 @@
 // ======================================
 
 // As our first piece of Rust code, we want to write a function that computes the
 // ======================================
 
 // As our first piece of Rust code, we want to write a function that computes the

-// minimum of a list. We are going to make use of the standard library, so let's import that:
+// minimum of a list.

 
 

+// We are going to make use of the standard library, so let's import that:

 use std;
 
 // Let us start by thinking about the *type* of our function. Rust forces us to give the types of
 use std;
 
 // Let us start by thinking about the *type* of our function. Rust forces us to give the types of


@@ -16,18 +17,18 @@ use std;
 // Coming from C(++), you can think of such a type as a `union`, together with a field that
 // stores the variant of the union that's currently used.
 
 // Coming from C(++), you can think of such a type as a `union`, together with a field that
 // stores the variant of the union that's currently used.
 

+// An `enum` for "a number or nothing" could look as follows:

 enum NumberOrNothing {
     Number(i32),
     Nothing
 }
 enum NumberOrNothing {
     Number(i32),
     Nothing
 }

-

 // Notice that `i32` is the type of (signed, 32-bit) integers. To write down the type of
 // the minimum function, we need just one more ingredient: `Vec<i32>` is the type of
 // (growable) arrays of numbers, and we will use that as our list type.
 // Notice that `i32` is the type of (signed, 32-bit) integers. To write down the type of
 // the minimum function, we need just one more ingredient: `Vec<i32>` is the type of
 // (growable) arrays of numbers, and we will use that as our list type.

-// Observe how in Rust, the return type comes *after* the arguments.

 
 

+// Observe how in Rust, the return type comes *after* the arguments.

 fn vec_min(vec: Vec<i32>) -> NumberOrNothing {
 fn vec_min(vec: Vec<i32>) -> NumberOrNothing {

-    // First, we need some variable to store the minimum as computed so far.
+    // In the function, we first need some variable to store the minimum as computed so far.

     // Since we start out with nothing computed, this will again be a 
     // "number or nothing":
     let mut min = NumberOrNothing::Nothing;
     // Since we start out with nothing computed, this will again be a 
     // "number or nothing":
     let mut min = NumberOrNothing::Nothing;


@@ -42,12 +43,12 @@ fn vec_min(vec: Vec<i32>) -> NumberOrNothing {
         // So `el` is al element of the list. We need to update `min` accordingly, but how do we get the current
         // number in there? This is what pattern matching can do:
         match min {
         // So `el` is al element of the list. We need to update `min` accordingly, but how do we get the current
         // number in there? This is what pattern matching can do:
         match min {

+            // In this case (*arm*) of the `match`, `min` is currently nothing, so let's just make it the number `el`.

             NumberOrNothing::Nothing => {
             NumberOrNothing::Nothing => {

-                // In this case (*arm*) of the `match`, `min` is currently nothing, so let's just make it the number `el`.

                 min = NumberOrNothing::Number(el);
             },
                 min = NumberOrNothing::Number(el);
             },

+            // In this arm, `min` is currently the number `n`, so let's compute the new minimum and store it.

             NumberOrNothing::Number(n) => {
             NumberOrNothing::Number(n) => {

-                // In this arm, `min` is currently the number `n`, so let's compute the new minimum and store it.

                 let new_min = std::cmp::min(n, el);
                 min = NumberOrNothing::Number(new_min);
             }
                 let new_min = std::cmp::min(n, el);
                 min = NumberOrNothing::Number(new_min);
             }


@@ -58,18 +59,20 @@ fn vec_min(vec: Vec<i32>) -> NumberOrNothing {
 }
 
 // Phew. We wrote our first Rust function! But all this `NumberOrNothing::` is getting kind of
 }
 
 // Phew. We wrote our first Rust function! But all this `NumberOrNothing::` is getting kind of

-// ugly. Can't we do that nicer? Indeed, we can: The following line tells Rust to take
-// the constructors of `NumberOrNothing` into the local namespace:
-use self::NumberOrNothing::{Number,Nothing};
+// ugly. Can't we do that nicer?
+
+// Indeed, we can: The following line tells Rust to take
+// the constructors of `NumberOrNothing` into the local namespace.

 // Try moving that above the function, and removing all the occurrences `NumberOrNothing::`.
 // Try moving that above the function, and removing all the occurrences `NumberOrNothing::`.

+use self::NumberOrNothing::{Number,Nothing};

 
 // To call this function, we now just need a list. Of course, ultimately we want to ask the user for
 
 // To call this function, we now just need a list. Of course, ultimately we want to ask the user for

-// a list of numbers, but for now, let's just hard-code something:
+// a list of numbers, but for now, let's just hard-code something.

 
 

+// `vec!` is a *macro* (as you can tell from the `!`) that constructs a constant `Vec<_>` with the given
+// elements.

 fn read_vec() -> Vec<i32> {
     vec![18,5,7,1,9,27]
 fn read_vec() -> Vec<i32> {
     vec![18,5,7,1,9,27]

-    // `vec!` is a *macro* (as you can tell from the `!`) that constructs a constant `Vec<_>` with the given
-    // elements.

 }
 
 // Finally, let's call our functions and run the code!
 }
 
 // Finally, let's call our functions and run the code!


@@ -77,18 +80,17 @@ fn read_vec() -> Vec<i32> {
 // Of course Rust can print numbers, but after calling `vec_min`, we have a `NumberOrNothing`.
 // So let's write a small helper function that prints such values.
 
 // Of course Rust can print numbers, but after calling `vec_min`, we have a `NumberOrNothing`.
 // So let's write a small helper function that prints such values.
 

+// `println!` is again a macro, where the first argument is a *format string*. For
+// now, you just need to know that `{}` is the placeholder for a value, and that Rust
+// will check at compile-time that you supplied the right number of arguments.

 fn print_number_or_nothing(n: NumberOrNothing) {
     match n {
         Nothing => println!("The number is: <nothing>"),
         Number(n) => println!("The number is: {}", n),
 fn print_number_or_nothing(n: NumberOrNothing) {
     match n {
         Nothing => println!("The number is: <nothing>"),
         Number(n) => println!("The number is: {}", n),

-        // `println!` is again a macro, where the first argument is a *format string*. For
-        // now, you just need to know that `{}` is the placeholder for a value, and that Rust
-        // will check at compile-time that you supplied the right number of arguments.

     };
 }
 
 // Putting it all together:
     };
 }
 
 // Putting it all together:

-

 pub fn part_main() {
     let vec = read_vec();
     let min = vec_min(vec);
 pub fn part_main() {
     let vec = read_vec();
     let min = vec_min(vec);

diff --git a/src/part01.rs b/src/part01.rs
index 7d66385f4a53970518cb2a06ae995f623e5d0523..7603c1fa79593467d63c354c293d3bef21b07437 100644 (file)
--- a/src/part01.rs
+++ b/src/part01.rs
@@ -8,13 +8,13 @@ use std;
 // understand that Rust is an "expression-based" language. This means that most of the
 // terms you write down are not just *statements* (executing code), but *expressions*
 // (returning a value). This applies even to the body of entire functions!
 // understand that Rust is an "expression-based" language. This means that most of the
 // terms you write down are not just *statements* (executing code), but *expressions*
 // (returning a value). This applies even to the body of entire functions!

-// 
+

 // For example, consider `sqr`:
 fn sqr(i: i32) -> i32 { i * i }
 // Between the curly braces, we are giving the *expression* that computes the return value.
 // So we can just write `i * i`, the expression that returns the square if `i`!
 // This is very close to how mathematicians write down functions (but with more types).
 // For example, consider `sqr`:
 fn sqr(i: i32) -> i32 { i * i }
 // Between the curly braces, we are giving the *expression* that computes the return value.
 // So we can just write `i * i`, the expression that returns the square if `i`!
 // This is very close to how mathematicians write down functions (but with more types).

-// 
+

 // Conditionals are also just expressions. You can compare this to the ternary `? :` operator
 // from languages like C.
 fn abs(i: i32) -> i32 { if i >= 0 { i } else { -i } }
 // Conditionals are also just expressions. You can compare this to the ternary `? :` operator
 // from languages like C.
 fn abs(i: i32) -> i32 { if i >= 0 { i } else { -i } }


@@ -42,10 +42,11 @@ fn number_or_default(n: NumberOrNothing, default: i32) -> i32 {
 fn vec_min(v: &Vec<i32>) -> NumberOrNothing {
     let mut min = Nothing;
     for e in v {
 fn vec_min(v: &Vec<i32>) -> NumberOrNothing {
     let mut min = Nothing;
     for e in v {

+        // Now that `v` is just a reference, the same goes for `e`, so we have to dereference the pointer.

         let e = *e;
         // Notice that all we do here is compute a new value for `min`, and that it will always end
         // up being a `Number` rather than `Nothing`. In Rust, the structure of the code
         let e = *e;
         // Notice that all we do here is compute a new value for `min`, and that it will always end
         // up being a `Number` rather than `Nothing`. In Rust, the structure of the code

-        // can express this uniformity as follows:
+        // can express this uniformity.

         min = Number(match min {
             Nothing => e,
             Number(n) => std::cmp::min(n, e)
         min = Number(match min {
             Nothing => e,
             Number(n) => std::cmp::min(n, e)


@@ -63,7 +64,7 @@ fn vec_min(v: &Vec<i32>) -> NumberOrNothing {
 // So much for `vec_min`. Let us now reconsider `print_number_or_nothing`. That function
 // really belongs pretty close to the type `NumberOrNothing`. In C++ or Java, you would
 // probably make it a method of the type. In Rust, we can achieve something very similar
 // So much for `vec_min`. Let us now reconsider `print_number_or_nothing`. That function
 // really belongs pretty close to the type `NumberOrNothing`. In C++ or Java, you would
 // probably make it a method of the type. In Rust, we can achieve something very similar

-// by providing an *inherent implementation* as follows:
+// by providing an *inherent implementation*.

 impl NumberOrNothing {
     fn print(self) {
         match self {
 impl NumberOrNothing {
     fn print(self) {
         match self {

diff --git a/src/part02.rs b/src/part02.rs
index 32fbe0a8ff296c4455878f1a71ae8db894f8a3aa..72dcddcac70043663e27f56d38b864d74536a51a 100644 (file)
--- a/src/part02.rs
+++ b/src/part02.rs
@@ -7,11 +7,11 @@ use std;
 // annoying that we had to hard-code the type `i32` in there? What if tomorrow,
 // we want a `CharOrNothing`, and later a `FloatOrNothing`? Certainly we don't
 // want to re-write the type and all its inherent methods.
 // annoying that we had to hard-code the type `i32` in there? What if tomorrow,
 // we want a `CharOrNothing`, and later a `FloatOrNothing`? Certainly we don't
 // want to re-write the type and all its inherent methods.

-// 
+

 // The solution to this is called *generics* or *polymorphism* (the latter is Greek,
 // meaning "many shapes"). You may know something similar from C++ (where it's called
 // The solution to this is called *generics* or *polymorphism* (the latter is Greek,
 // meaning "many shapes"). You may know something similar from C++ (where it's called

-// *templates*) or Java, or one of the many functional languages. A generic
-// `SomethingOrNothing` type looks as follows:
+// *templates*) or Java, or one of the many functional languages. So here, we define
+// a generic `SomethingOrNothing` type.

 enum SomethingOrNothing<T>  {
     Something(T),
     Nothing,
 enum SomethingOrNothing<T>  {
     Something(T),
     Nothing,


@@ -25,4 +25,36 @@ use self::SomethingOrNothing::{Something,Nothing};
 // Go check out its [documentation](http://doc.rust-lang.org/stable/std/option/index.html)!
 // (And don't worry, there's indeed lots of material mentioned there that we did not cover yet.)
 
 // Go check out its [documentation](http://doc.rust-lang.org/stable/std/option/index.html)!
 // (And don't worry, there's indeed lots of material mentioned there that we did not cover yet.)
 

-// [index](main.html) | [previous](part01.html) | [next](part03.html)
+// **Exercise**: Write functions converting between `SomethingOrNothing<T>` and `Option<T>`. You will have to use
+// the names of the constructor of `Option`, which you can find in the documentation I linked above.
+
+// Here's a skeleton for your solution, you only have to fill in the function bodies.
+// (`panic!` is, again, a macro - this one terminates execution when it is reached).
+// 
+// Notice the syntax for giving generic implementations to generic types: Think of the first `<T>` 
+// as *declaring* a type variable ("I am doing something for all types `T`"), and the second `<T>` as
+// *using* that variable ("The thing I do, is implement `SomethingOrNothing<T>`").
+impl<T> SomethingOrNothing<T> {
+    fn new(o: Option<T>) -> Self {
+        panic!("Not yet implemented.");
+    }
+
+    fn to_option(self) -> Option<T> {
+        panic!("Not yet implemented.");
+    }
+}
+// Inside an `impl`, `Self` refers to the type we are implementing things for. Here, it is
+// an alias for `SomethingOrNothing<T>`.
+// Remember that `self` is the `this` of Rust, and implicitly has type `Self`.
+// 
+// Observe how `new` does *not* have a `self` parameter. This corresponds to a `static` method
+// in Java or C++. In fact, `new` is the Rust convention for defining constructors: They are
+// nothing special, just static functions returning `Self`.
+
+// You can call static functions, and in particular constructors, as follows:
+fn call_constructor(x: i32) -> SomethingOrNothing<i32> {
+    SomethingOrNothing::new(Some(x))
+}
+    
+
+// [index](main.html) | [previous](part01.html) | next