summaryrefslogtreecommitdiffhomepage
path: root/d.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'd.html.markdown')
-rw-r--r--d.html.markdown101
1 files changed, 57 insertions, 44 deletions
diff --git a/d.html.markdown b/d.html.markdown
index ba24b60f..edb3bff5 100644
--- a/d.html.markdown
+++ b/d.html.markdown
@@ -23,8 +23,10 @@ about [D](http://dlang.org/). The D programming language is a modern, general-pu
multi-paradigm language with support for everything from low-level features to
expressive high-level abstractions.
-D is actively developed by Walter Bright and Andrei Alexandrescu, two super smart, really cool
-dudes. With all that out of the way, let's look at some examples!
+D is actively developed by a large group of super-smart people and is spearheaded by
+[Walter Bright](https://en.wikipedia.org/wiki/Walter_Bright) and
+[Andrei Alexandrescu](https://en.wikipedia.org/wiki/Andrei_Alexandrescu).
+With all that out of the way, let's look at some examples!
```c
import std.stdio;
@@ -36,9 +38,10 @@ void main() {
writeln(i);
}
- auto n = 1; // use auto for type inferred variables
+ // 'auto' can be used for inferring types.
+ auto n = 1;
- // Numeric literals can use _ as a digit seperator for clarity
+ // Numeric literals can use '_' as a digit separator for clarity.
while(n < 10_000) {
n += n;
}
@@ -47,16 +50,18 @@ void main() {
n -= (n / 2);
} while(n > 0);
- // For and while are nice, but in D-land we prefer foreach
- // The .. creates a continuous range, excluding the end
- foreach(i; 1..1_000_000) {
+ // For and while are nice, but in D-land we prefer 'foreach' loops.
+ // The '..' creates a continuous range, including the first value
+ // but excluding the last.
+ foreach(n; 1..1_000_000) {
if(n % 2 == 0)
- writeln(i);
+ writeln(n);
}
- foreach_reverse(i; 1..int.max) {
+ // There's also 'foreach_reverse' when you want to loop backwards.
+ foreach_reverse(n; 1..int.max) {
if(n % 2 == 1) {
- writeln(i);
+ writeln(n);
} else {
writeln("No!");
}
@@ -65,20 +70,22 @@ void main() {
```
We can define new types with `struct`, `class`, `union`, and `enum`. Structs and unions
-are passed to functions by value (i.e. copied) and classes are passed by reference. Futhermore,
+are passed to functions by value (i.e. copied) and classes are passed by reference. Furthermore,
we can use templates to parameterize all of these on both types and values!
```c
-// Here, T is a type parameter. Think <T> from C++/C#/Java
+// Here, 'T' is a type parameter. Think '<T>' from C++/C#/Java.
struct LinkedList(T) {
T data = null;
- LinkedList!(T)* next; // The ! is used to instaniate a parameterized type. Again, think <T>
+
+ // Use '!' to instantiate a parameterized type. Again, think '<T>'.
+ LinkedList!(T)* next;
}
class BinTree(T) {
T data = null;
- // If there is only one template parameter, we can omit parens
+ // If there is only one template parameter, we can omit the parentheses.
BinTree!T left;
BinTree!T right;
}
@@ -93,13 +100,11 @@ enum Day {
Saturday,
}
-// Use alias to create abbreviations for types
-
+// Use alias to create abbreviations for types.
alias IntList = LinkedList!int;
alias NumTree = BinTree!double;
// We can create function templates as well!
-
T max(T)(T a, T b) {
if(a < b)
return b;
@@ -107,9 +112,8 @@ T max(T)(T a, T b) {
return a;
}
-// Use the ref keyword to ensure pass by referece.
-// That is, even if a and b are value types, they
-// will always be passed by reference to swap
+// Use the ref keyword to ensure pass by reference. That is, even if 'a' and 'b'
+// are value types, they will always be passed by reference to 'swap()'.
void swap(T)(ref T a, ref T b) {
auto temp = a;
@@ -117,13 +121,13 @@ void swap(T)(ref T a, ref T b) {
b = temp;
}
-// With templates, we can also parameterize on values, not just types
+// With templates, we can also parameterize on values, not just types.
class Matrix(uint m, uint n, T = int) {
T[m] rows;
T[n] columns;
}
-auto mat = new Matrix!(3, 3); // We've defaulted type T to int
+auto mat = new Matrix!(3, 3); // We've defaulted type 'T' to 'int'.
```
@@ -133,21 +137,20 @@ have the syntax of POD structures (`structure.x = 7`) with the semantics of
getter and setter methods (`object.setX(7)`)!
```c
-// Consider a class parameterized on a types T, U
-
+// Consider a class parameterized on types 'T' & 'U'.
class MyClass(T, U) {
T _data;
U _other;
-
}
-// And "getter" and "setter" methods like so
+// And "getter" and "setter" methods like so:
class MyClass(T, U) {
T _data;
U _other;
- // Constructors are always named `this`
+ // Constructors are always named 'this'.
this(T t, U u) {
+ // This will call the setter methods below.
data = t;
other = u;
}
@@ -170,16 +173,24 @@ class MyClass(T, U) {
_other = u;
}
}
-// And we use them in this manner
+// And we use them in this manner:
void main() {
- auto mc = MyClass!(int, string);
+ auto mc = new MyClass!(int, string)(7, "seven");
- mc.data = 7;
- mc.other = "seven";
+ // Import the 'stdio' module from the standard library for writing to
+ // console (imports can be local to a scope).
+ import std.stdio;
- writeln(mc.data);
- writeln(mc.other);
+ // Call the getters to fetch the values.
+ writefln("Earlier: data = %d, str = %s", mc.data, mc.other);
+
+ // Call the setters to assign new values.
+ mc.data = 8;
+ mc.other = "eight";
+
+ // Call the getters again to fetch the new values.
+ writefln("Later: data = %d, str = %s", mc.data, mc.other);
}
```
@@ -188,8 +199,8 @@ our getter and setter methods, and keep the clean syntax of
accessing members directly!
Other object-oriented goodies at our disposal
-include `interface`s, `abstract class`es,
-and `override`ing methods. D does inheritance just like Java:
+include interfaces, abstract classes,
+and overriding methods. D does inheritance just like Java:
Extend one class, implement as many interfaces as you please.
We've seen D's OOP facilities, but let's switch gears. D offers
@@ -207,7 +218,7 @@ void main() {
// from 1 to 100. Easy!
// Just pass lambda expressions as template parameters!
- // You can pass any old function you like, but lambdas are convenient here.
+ // You can pass any function you like, but lambdas are convenient here.
auto num = iota(1, 101).filter!(x => x % 2 == 0)
.map!(y => y ^^ 2)
.reduce!((a, b) => a + b);
@@ -217,7 +228,7 @@ void main() {
```
Notice how we got to build a nice Haskellian pipeline to compute num?
-That's thanks to a D innovation know as Uniform Function Call Syntax.
+That's thanks to a D innovation know as Uniform Function Call Syntax (UFCS).
With UFCS, we can choose whether to write a function call as a method
or free function call! Walter wrote a nice article on this
[here.](http://www.drdobbs.com/cpp/uniform-function-call-syntax/232700394)
@@ -227,21 +238,23 @@ is of some type A on any expression of type A as a method.
I like parallelism. Anyone else like parallelism? Sure you do. Let's do some!
```c
+// Let's say we want to populate a large array with the square root of all
+// consecutive integers starting from 1 (up until the size of the array), and we
+// want to do this concurrently taking advantage of as many cores as we have
+// available.
+
import std.stdio;
import std.parallelism : parallel;
import std.math : sqrt;
void main() {
- // We want take the square root every number in our array,
- // and take advantage of as many cores as we have available.
+ // Create your large array
auto arr = new double[1_000_000];
- // Use an index, and an array element by referece,
- // and just call parallel on the array!
+ // Use an index, access every array element by reference (because we're
+ // going to change each element) and just call parallel on the array!
foreach(i, ref elem; parallel(arr)) {
- ref = sqrt(i + 1.0);
+ elem = sqrt(i + 1.0);
}
}
-
-
```