odin-lang.Odin/examples/demo/demo.odin

package main

import "core:fmt"
import "core:mem"
import "core:os"
import "core:thread"
import "core:time"
import "core:reflect"
import "core:runtime"
import "core:intrinsics"


/*
	The Odin programming language is fast, concise, readable, pragmatic and open sourced.
	It is designed with the intent of replacing C with the following goals:
	 * simplicity
	 * high performance
	 * built for modern systems
	 * joy of programming

	# Installing Odin
	Getting Started - https://odin-lang.org/docs/install/
		Instructions for downloading and install the Odin compiler and libraries.

	# Learning Odin
	Overview of Odin - https://odin-lang.org/docs/overview/
		An overview of the Odin programming language.
	Frequently Asked Questions (FAQ) - https://odin-lang.org/docs/faq/
		Answers to common questions about Odin.
*/

the_basics :: proc() {
	fmt.println("\n# the basics");

	{ // The Basics
		fmt.println("Hellope");

		// Lexical elements and literals
		// A comment

		my_integer_variable: int; // A comment for documentaton

		// Multi-line comments begin with /* and end with */. Multi-line comments can
		// also be nested (unlike in C):
		/*
			You can have any text or code here and
			have it be commented.
			/*
				NOTE: comments can be nested!
			*/
		*/

		// String literals are enclosed in double quotes and character literals in single quotes.
		// Special characters are escaped with a backslash \

		some_string := "This is a string";
		_ = 'A'; // unicode codepoint literal
		_ = '\n';
		_ = "C:\\Windows\\notepad.exe";
		// Raw string literals are enclosed with single back ticks
		_ = `C:\Windows\notepad.exe`;

		// The length of a string in bytes can be found using the built-in `len` procedure:
		_ = len("Foo");
		_ = len(some_string);


		// Numbers

		// Numerical literals are written similar to most other programming languages.
		// A useful feature in Odin is that underscores are allowed for better
		// readability: 1_000_000_000 (one billion). A number that contains a dot is a
		// floating point literal: 1.0e9 (one billion). If a number literal is suffixed
		// with i, is an imaginary number literal: 2i (2 multiply the square root of -1).

		// Binary literals are prefixed with 0b, octal literals with 0o, and hexadecimal
		// literals 0x. A leading zero does not produce an octal constant (unlike C).

		// In Odin, if a numeric constant can be represented by a type without
		// precision loss, it will automatically convert to that type.

		x: int = 1.0; // A float literal but it can be represented by an integer without precision loss
		// Constant literals are “untyped” which means that they can implicitly convert to a type.

		y: int; // `y` is typed of type `int`
		y = 1;  // `1` is an untyped integer literal which can implicitly convert to `int`

		z: f64; // `z` is typed of type `f64` (64-bit floating point number)
		z = 1;  // `1` is an untyped integer literal which can be implicitly converted to `f64`
				// No need for any suffixes or decimal places like in other languages
				// CONSTANTS JUST WORK!!!


		// Assignment statements
		h: int = 123; // declares a new variable `h` with type `int` and assigns a value to it
		h = 637; // assigns a new value to `h`

		// `=` is the assignment operator

		// You can assign multiple variables with it:
		a, b := 1, "hello"; // declares `a` and `b` and infers the types from the assignments
		b, a = "byte", 0;

		// Note: `:=` is two tokens, `:` and `=`. The following are equivalent,
		/*
			i: int = 123;
			i:     = 123;
			i := 123;
		*/

		// Constant declarations
		// Constants are entities (symbols) which have an assigned value.
		// The constant’s value cannot be changed.
		// The constant’s value must be able to be evaluated at compile time:
		X :: "what"; // constant `X` has the untyped string value "what"

		// Constants can be explicitly typed like a variable declaration:
		Y : int : 123;
		Z :: Y + 7; // constant computations are possible

		_ = my_integer_variable;
		_ = x;
	}
}

control_flow :: proc() {
	fmt.println("\n# control flow");
	{ // Control flow
		// For loop
		// Odin has only one loop statement, the `for` loop

		// Basic for loop
		for i := 0; i < 10; i += 1 {
			fmt.println(i);
		}

		// NOTE: Unlike other languages like C, there are no parentheses `( )` surrounding the three components.
		// Braces `{ }` or a `do` are always required
		for i := 0; i < 10; i += 1 { }
		// for i := 0; i < 10; i += 1 do fmt.print();

		// The initial and post statements are optional
		i := 0;
		for ; i < 10; {
			i += 1;
		}

		// These semicolons can be dropped. This `for` loop is equivalent to C's `while` loop
		i = 0;
		for i < 10 {
			i += 1;
		}

		// If the condition is omitted, an infinite loop is produced:
		for {
			break;
		}

		// Range-based for loop
		// The basic for loop
		for j := 0; j < 10; j += 1 {
			fmt.println(j);
		}
		// can also be written
		for j in 0..<10 {
			fmt.println(j);
		}
		for j in 0..=9 {
			fmt.println(j);
		}

		// Certain built-in types can be iterated over
		some_string := "Hello, 世界";
		for character in some_string { // Strings are assumed to be UTF-8
			fmt.println(character);
		}

		some_array := [3]int{1, 4, 9};
		for value in some_array {
			fmt.println(value);
		}

		some_slice := []int{1, 4, 9};
		for value in some_slice {
			fmt.println(value);
		}

		some_dynamic_array := [dynamic]int{1, 4, 9};
		defer delete(some_dynamic_array);
		for value in some_dynamic_array {
			fmt.println(value);
		}


		some_map := map[string]int{"A" = 1, "C" = 9, "B" = 4};
		defer delete(some_map);
		for key in some_map {
			fmt.println(key);
		}

		// Alternatively a second index value can be added
		for character, index in some_string {
			fmt.println(index, character);
		}
		for value, index in some_array {
			fmt.println(index, value);
		}
		for value, index in some_slice {
			fmt.println(index, value);
		}
		for value, index in some_dynamic_array {
			fmt.println(index, value);
		}
		for key, value in some_map {
			fmt.println(key, value);
		}

		// The iterated values are copies and cannot be written to.
		// The following idiom is useful for iterating over a container in a by-reference manner:
		for _, idx in some_slice {
			some_slice[idx] = (idx+1)*(idx+1);
		}


		// If statements
		x := 123;
		if x >= 0 {
			fmt.println("x is positive");
		}

		if y := -34; y < 0 {
			fmt.println("y is negative");
		}

		if y := 123; y < 0 {
			fmt.println("y is negative");
		} else if y == 0 {
			fmt.println("y is zero");
		} else {
			fmt.println("y is positive");
		}

		// Switch statement
		// A switch statement is another way to write a sequence of if-else statements.
		// In Odin, the default case is denoted as a case without any expression.

		switch arch := ODIN_ARCH; arch {
		case "386":
			fmt.println("32-bit");
		case "amd64":
			fmt.println("64-bit");
		case: // default
			fmt.println("Unsupported architecture");
		}

		// Odin’s `switch` is like one in C or C++, except that Odin only runs the selected case.
		// This means that a `break` statement is not needed at the end of each case.
		// Another important difference is that the case values need not be integers nor constants.

		// To achieve a C-like fall through into the next case block, the keyword `fallthrough` can be used.
		one_angry_dwarf :: proc() -> int {
			fmt.println("one_angry_dwarf was called");
			return 1;
		}

		switch j := 0; j {
		case 0:
		case one_angry_dwarf():
		}

		// A switch statement without a condition is the same as `switch true`.
		// This can be used to write a clean and long if-else chain and have the
		// ability to break if needed

		switch {
		case x < 0:
			fmt.println("x is negative");
		case x == 0:
			fmt.println("x is zero");
		case:
			fmt.println("x is positive");
		}

		// A `switch` statement can also use ranges like a range-based loop:
		switch c := 'j'; c {
		case 'A'..='Z', 'a'..='z', '0'..='9':
			fmt.println("c is alphanumeric");
		}

		switch x {
		case 0..<10:
			fmt.println("units");
		case 10..<13:
			fmt.println("pre-teens");
		case 13..<20:
			fmt.println("teens");
		case 20..<30:
			fmt.println("twenties");
		}
	}

	{ // Defer statement
		// A defer statement defers the execution of a statement until the end of
		// the scope it is in.

		// The following will print 4 then 234:
		{
			x := 123;
			defer fmt.println(x);
			{
				defer x = 4;
				x = 2;
			}
			fmt.println(x);

			x = 234;
		}

		// You can defer an entire block too:
		{
			bar :: proc() {}

			defer {
				fmt.println("1");
				fmt.println("2");
			}

			cond := false;
			defer if cond {
				bar();
			}
		}

		// Defer statements are executed in the reverse order that they were declared:
		{
			defer fmt.println("1");
			defer fmt.println("2");
			defer fmt.println("3");
		}
		// Will print 3, 2, and then 1.

		if false {
			f, err := os.open("my_file.txt");
			if err != 0 {
				// handle error
			}
			defer os.close(f);
			// rest of code
		}
	}

	{ // When statement
		/*
			The when statement is almost identical to the if statement but with some differences:

			* Each condition must be a constant expression as a when
			  statement is evaluated at compile time.
			* The statements within a branch do not create a new scope
			* The compiler checks the semantics and code only for statements
			  that belong to the first condition that is true
			* An initial statement is not allowed in a when statement
			* when statements are allowed at file scope
		*/

		// Example
		when ODIN_ARCH == "386" {
			fmt.println("32 bit");
		} else when ODIN_ARCH == "amd64" {
			fmt.println("64 bit");
		} else {
			fmt.println("Unsupported architecture");
		}
		// The when statement is very useful for writing platform specific code.
		// This is akin to the #if construct in C’s preprocessor however, in Odin,
		// it is type checked.
	}

	{ // Branch statements
		cond, cond1, cond2 := false, false, false;
		one_step :: proc() { fmt.println("one_step"); }
		beyond :: proc() { fmt.println("beyond"); }

		// Break statement
		for cond {
			switch {
			case:
				if cond {
					break; // break out of the `switch` statement
				}
			}

			break; // break out of the `for` statement
		}

		loop: for cond1 {
			for cond2 {
				break loop; // leaves both loops
			}
		}

		// Continue statement
		for cond {
			if cond2 {
				continue;
			}
			fmt.println("Hellope");
		}

		// Fallthrough statement

		// Odin’s switch is like one in C or C++, except that Odin only runs the selected
		// case. This means that a break statement is not needed at the end of each case.
		// Another important difference is that the case values need not be integers nor
		// constants.

		// fallthrough can be used to explicitly fall through into the next case block:

		switch i := 0; i {
		case 0:
			one_step();
			fallthrough;
		case 1:
			beyond();
		}
	}
}


named_proc_return_parameters :: proc() {
	fmt.println("\n# named proc return parameters");

	foo0 :: proc() -> int {
		return 123;
	}
	foo1 :: proc() -> (a: int) {
		a = 123;
		return;
	}
	foo2 :: proc() -> (a, b: int) {
		// Named return values act like variables within the scope
		a = 321;
		b = 567;
		return b, a;
	}
	fmt.println("foo0 =", foo0()); // 123
	fmt.println("foo1 =", foo1()); // 123
	fmt.println("foo2 =", foo2()); // 567 321
}


explicit_procedure_overloading :: proc() {
	fmt.println("\n# explicit procedure overloading");

	add_ints :: proc(a, b: int) -> int {
		x := a + b;
		fmt.println("add_ints", x);
		return x;
	}
	add_floats :: proc(a, b: f32) -> f32 {
		x := a + b;
		fmt.println("add_floats", x);
		return x;
	}
	add_numbers :: proc(a: int, b: f32, c: u8) -> int {
		x := int(a) + int(b) + int(c);
		fmt.println("add_numbers", x);
		return x;
	}

	add :: proc{add_ints, add_floats, add_numbers};

	add(int(1), int(2));
	add(f32(1), f32(2));
	add(int(1), f32(2), u8(3));

	add(1, 2);     // untyped ints coerce to int tighter than f32
	add(1.0, 2.0); // untyped floats coerce to f32 tighter than int
	add(1, 2, 3);  // three parameters

	// Ambiguous answers
	// add(1.0, 2);
	// add(1, 2.0);
}

struct_type :: proc() {
	fmt.println("\n# struct type");
	// A struct is a record type in Odin. It is a collection of fields.
	// Struct fields are accessed by using a dot:
	{
		Vector2 :: struct {
			x: f32,
			y: f32,
		};
		v := Vector2{1, 2};
		v.x = 4;
		fmt.println(v.x);

		// Struct fields can be accessed through a struct pointer:

		v = Vector2{1, 2};
		p := &v;
		p.x = 1335;
		fmt.println(v);

		// We could write p^.x, however, it is to nice abstract the ability
		// to not explicitly dereference the pointer. This is very useful when
		// refactoring code to use a pointer rather than a value, and vice versa.
	}
	{
		// A struct literal can be denoted by providing the struct’s type
		// followed by {}. A struct literal must either provide all the
		// arguments or none:
		Vector3 :: struct {
			x, y, z: f32,
		};
		v: Vector3;
		v = Vector3{}; // Zero value
		v = Vector3{1, 4, 9};

		// You can list just a subset of the fields if you specify the
		// field by name (the order of the named fields does not matter):
		v = Vector3{z=1, y=2};
		assert(v.x == 0);
		assert(v.y == 2);
		assert(v.z == 1);
	}
	{
		// Structs can tagged with different memory layout and alignment requirements:

		a :: struct #align 4   {}; // align to 4 bytes
		b :: struct #packed    {}; // remove padding between fields
		c :: struct #raw_union {}; // all fields share the same offset (0). This is the same as C's union
	}

}


union_type :: proc() {
	fmt.println("\n# union type");
	{
		val: union{int, bool};
		val = 137;
		if i, ok := val.(int); ok {
			fmt.println(i);
		}
		val = true;
		fmt.println(val);

		val = nil;

		switch v in val {
		case int:  fmt.println("int",  v);
		case bool: fmt.println("bool", v);
		case:      fmt.println("nil");
		}
	}
	{
		// There is a duality between `any` and `union`
		// An `any` has a pointer to the data and allows for any type (open)
		// A `union` has as binary blob to store the data and allows only certain types (closed)
		// The following code is with `any` but has the same syntax
		val: any;
		val = 137;
		if i, ok := val.(int); ok {
			fmt.println(i);
		}
		val = true;
		fmt.println(val);

		val = nil;

		switch v in val {
		case int:  fmt.println("int",  v);
		case bool: fmt.println("bool", v);
		case:      fmt.println("nil");
		}
	}

	Vector3 :: distinct [3]f32;
	Quaternion :: distinct quaternion128;

	// More realistic examples
	{
		// NOTE(bill): For the above basic examples, you may not have any
		// particular use for it. However, my main use for them is not for these
		// simple cases. My main use is for hierarchical types. Many prefer
		// subtyping, embedding the base data into the derived types. Below is
		// an example of this for a basic game Entity.

		Entity :: struct {
			id:          u64,
			name:        string,
			position:    Vector3,
			orientation: Quaternion,

			derived: any,
		};

		Frog :: struct {
			using entity: Entity,
			jump_height:  f32,
		};

		Monster :: struct {
			using entity: Entity,
			is_robot:     bool,
			is_zombie:    bool,
		};

		// See `parametric_polymorphism` procedure for details
		new_entity :: proc($T: typeid) -> ^Entity {
			t := new(T);
			t.derived = t^;
			return t;
		}

		entity := new_entity(Monster);

		switch e in entity.derived {
		case Frog:
			fmt.println("Ribbit");
		case Monster:
			if e.is_robot  { fmt.println("Robotic"); }
			if e.is_zombie { fmt.println("Grrrr!");  }
			fmt.println("I'm a monster");
		}
	}

	{
		// NOTE(bill): A union can be used to achieve something similar. Instead
		// of embedding the base data into the derived types, the derived data
		// in embedded into the base type. Below is the same example of the
		// basic game Entity but using an union.

		Entity :: struct {
			id:          u64,
			name:        string,
			position:    Vector3,
			orientation: Quaternion,

			derived: union {Frog, Monster},
		};

		Frog :: struct {
			using entity: ^Entity,
			jump_height:  f32,
		};

		Monster :: struct {
			using entity: ^Entity,
			is_robot:     bool,
			is_zombie:    bool,
		};

		// See `parametric_polymorphism` procedure for details
		new_entity :: proc($T: typeid) -> ^Entity {
			t := new(Entity);
			t.derived = T{entity = t};
			return t;
		}

		entity := new_entity(Monster);

		switch e in entity.derived {
		case Frog:
			fmt.println("Ribbit");
		case Monster:
			if e.is_robot  { fmt.println("Robotic"); }
			if e.is_zombie { fmt.println("Grrrr!");  }
		}

		// NOTE(bill): As you can see, the usage code has not changed, only its
		// memory layout. Both approaches have their own advantages but they can
		// be used together to achieve different results. The subtyping approach
		// can allow for a greater control of the memory layout and memory
		// allocation, e.g. storing the derivatives together. However, this is
		// also its disadvantage. You must either preallocate arrays for each
		// derivative separation (which can be easily missed) or preallocate a
		// bunch of "raw" memory; determining the maximum size of the derived
		// types would require the aid of metaprogramming. Unions solve this
		// particular problem as the data is stored with the base data.
		// Therefore, it is possible to preallocate, e.g. [100]Entity.

		// It should be noted that the union approach can have the same memory
		// layout as the any and with the same type restrictions by using a
		// pointer type for the derivatives.

		/*
			Entity :: struct {
				...
				derived: union{^Frog, ^Monster},
			}

			Frog :: struct {
				using entity: Entity,
				...
			}
			Monster :: struct {
				using entity: Entity,
				...

			}
			new_entity :: proc(T: type) -> ^Entity {
				t := new(T);
				t.derived = t;
				return t;
			}
		*/
	}
}

using_statement :: proc() {
	fmt.println("\n# using statement");
	// using can used to bring entities declared in a scope/namespace
	// into the current scope. This can be applied to import names, struct
	// fields, procedure fields, and struct values.

	Vector3 :: struct{x, y, z: f32};
	{
		Entity :: struct {
			position: Vector3,
			orientation: quaternion128,
		};

		// It can used like this:
		foo0 :: proc(entity: ^Entity) {
			fmt.println(entity.position.x, entity.position.y, entity.position.z);
		}

		// The entity members can be brought into the procedure scope by using it:
		foo1 :: proc(entity: ^Entity) {
			using entity;
			fmt.println(position.x, position.y, position.z);
		}

		// The using can be applied to the parameter directly:
		foo2 :: proc(using entity: ^Entity) {
			fmt.println(position.x, position.y, position.z);
		}

		// It can also be applied to sub-fields:
		foo3 :: proc(entity: ^Entity) {
			using entity.position;
			fmt.println(x, y, z);
		}
	}
	{
		// We can also apply the using statement to the struct fields directly,
		// making all the fields of position appear as if they on Entity itself:
		Entity :: struct {
			using position: Vector3,
			orientation: quaternion128,
		};
		foo :: proc(entity: ^Entity) {
			fmt.println(entity.x, entity.y, entity.z);
		}


		// Subtype polymorphism
		// It is possible to get subtype polymorphism, similar to inheritance-like
		// functionality in C++, but without the requirement of vtables or unknown
		// struct layout:

		Colour :: struct {r, g, b, a: u8};
		Frog :: struct {
			ribbit_volume: f32,
			using entity: Entity,
			colour: Colour,
		};

		frog: Frog;
		// Both work
		foo(&frog.entity);
		foo(&frog);
		frog.x = 123;

		// Note: using can be applied to arbitrarily many things, which allows
		// the ability to have multiple subtype polymorphism (but also its issues).

		// Note: using’d fields can still be referred by name.
	}
}


implicit_context_system :: proc() {
	fmt.println("\n# implicit context system");
	// In each scope, there is an implicit value named context. This
	// context variable is local to each scope and is implicitly passed
	// by pointer to any procedure call in that scope (if the procedure
	// has the Odin calling convention).

	// The main purpose of the implicit context system is for the ability
	// to intercept third-party code and libraries and modify their
	// functionality. One such case is modifying how a library allocates
	// something or logs something. In C, this was usually achieved with
	// the library defining macros which could be overridden so that the
	// user could define what he wanted. However, not many libraries
	// supported this in many languages by default which meant intercepting
	// third-party code to see what it does and to change how it does it is
	// not possible.

	c := context; // copy the current scope's context

	context.user_index = 456;
	{
		context.allocator = my_custom_allocator();
		context.user_index = 123;
		what_a_fool_believes(); // the `context` for this scope is implicitly passed to `what_a_fool_believes`
	}

	// `context` value is local to the scope it is in
	assert(context.user_index == 456);

	what_a_fool_believes :: proc() {
		c := context; // this `context` is the same as the parent procedure that it was called from
		// From this example, context.user_index == 123
		// An context.allocator is assigned to the return value of `my_custom_allocator()`
		assert(context.user_index == 123);

		// The memory management procedure use the `context.allocator` by
		// default unless explicitly specified otherwise
		china_grove := new(int);
		free(china_grove);

		_ = c;
	}

	my_custom_allocator :: mem.nil_allocator;
	_ = c;

	// By default, the context value has default values for its parameters which is
	// decided in the package runtime. What the defaults are are compiler specific.

	// To see what the implicit context value contains, please see the following
	// definition in package runtime.
}

parametric_polymorphism :: proc() {
	fmt.println("\n# parametric polymorphism");

	print_value :: proc(value: $T) {
		fmt.printf("print_value: %T %v\n", value, value);
	}

	v1: int    = 1;
	v2: f32    = 2.1;
	v3: f64    = 3.14;
	v4: string = "message";

	print_value(v1);
	print_value(v2);
	print_value(v3);
	print_value(v4);

	fmt.println();

	add :: proc(p, q: $T) -> T {
		x: T = p + q;
		return x;
	}

	a := add(3, 4);
	fmt.printf("a: %T = %v\n", a, a);

	b := add(3.2, 4.3);
	fmt.printf("b: %T = %v\n", b, b);

	// This is how `new` is implemented
	alloc_type :: proc($T: typeid) -> ^T {
		t := cast(^T)alloc(size_of(T), align_of(T));
		t^ = T{}; // Use default initialization value
		return t;
	}

	copy_slice :: proc(dst, src: []$T) -> int {
		n := min(len(dst), len(src));
		if n > 0 {
			mem.copy(&dst[0], &src[0], n*size_of(T));
		}
		return n;
	}

	double_params :: proc(a: $A, b: $B) -> A {
		return a + A(b);
	}

	fmt.println(double_params(12, 1.345));



	{ // Polymorphic Types and Type Specialization
		Table_Slot :: struct($Key, $Value: typeid) {
			occupied: bool,
			hash:     u32,
			key:      Key,
			value:    Value,
		};
		TABLE_SIZE_MIN :: 32;
		Table :: struct($Key, $Value: typeid) {
			count:     int,
			allocator: mem.Allocator,
			slots:     []Table_Slot(Key, Value),
		};

		// Only allow types that are specializations of a (polymorphic) slice
		make_slice :: proc($T: typeid/[]$E, len: int) -> T {
			return make(T, len);
		}

		// Only allow types that are specializations of `Table`
		allocate :: proc(table: ^$T/Table, capacity: int) {
			c := context;
			if table.allocator.procedure != nil {
				c.allocator = table.allocator;
			}
			context = c;

			table.slots = make_slice(type_of(table.slots), max(capacity, TABLE_SIZE_MIN));
		}

		expand :: proc(table: ^$T/Table) {
			c := context;
			if table.allocator.procedure != nil {
				c.allocator = table.allocator;
			}
			context = c;

			old_slots := table.slots;
			defer delete(old_slots);

			cap := max(2*len(table.slots), TABLE_SIZE_MIN);
			allocate(table, cap);

			for s in old_slots {
				if s.occupied {
					put(table, s.key, s.value);
				}
			}
		}

		// Polymorphic determination of a polymorphic struct
		// put :: proc(table: ^$T/Table, key: T.Key, value: T.Value) {
		put :: proc(table: ^Table($Key, $Value), key: Key, value: Value) {
			hash := get_hash(key); // Ad-hoc method which would fail in a different scope
			index := find_index(table, key, hash);
			if index < 0 {
				if f64(table.count) >= 0.75*f64(len(table.slots)) {
					expand(table);
				}
				assert(table.count <= len(table.slots));

				index = int(hash % u32(len(table.slots)));

				for table.slots[index].occupied {
					if index += 1; index >= len(table.slots) {
						index = 0;
					}
				}

				table.count += 1;
			}

			slot := &table.slots[index];
			slot.occupied = true;
			slot.hash     = hash;
			slot.key      = key;
			slot.value    = value;
		}


		// find :: proc(table: ^$T/Table, key: T.Key) -> (T.Value, bool) {
		find :: proc(table: ^Table($Key, $Value), key: Key) -> (Value, bool) {
			hash := get_hash(key);
			index := find_index(table, key, hash);
			if index < 0 {
				return Value{}, false;
			}
			return table.slots[index].value, true;
		}

		find_index :: proc(table: ^Table($Key, $Value), key: Key, hash: u32) -> int {
			if len(table.slots) <= 0 {
				return -1;
			}

			index := int(hash % u32(len(table.slots)));
			for table.slots[index].occupied {
				if table.slots[index].hash == hash {
					if table.slots[index].key == key {
						return index;
					}
				}

				if index += 1; index >= len(table.slots) {
					index = 0;
				}
			}

			return -1;
		}

		get_hash :: proc(s: string) -> u32 { // fnv32a
			h: u32 = 0x811c9dc5;
			for i in 0..<len(s) {
				h = (h ~ u32(s[i])) * 0x01000193;
			}
			return h;
		}


		table: Table(string, int);

		for i in 0..=36 { put(&table, "Hellope", i); }
		for i in 0..=42 { put(&table, "World!",  i); }

		found, _ := find(&table, "Hellope");
		fmt.printf("`found` is %v\n", found);

		found, _ = find(&table, "World!");
		fmt.printf("`found` is %v\n", found);

		// I would not personally design a hash table like this in production
		// but this is a nice basic example
		// A better approach would either use a `u64` or equivalent for the key
		// and let the user specify the hashing function or make the user store
		// the hashing procedure with the table
	}

	{ // Parametric polymorphic union
		Error :: enum {
			Foo0,
			Foo1,
			Foo2,
			Foo3,
		};
		Para_Union :: union($T: typeid) {T, Error};
		r: Para_Union(int);
		fmt.println(typeid_of(type_of(r)));

		fmt.println(r);
		r = 123;
		fmt.println(r);
		r = Error.Foo0; // r = .Foo0; is allow too, see implicit selector expressions below
		fmt.println(r);
	}

	{ // Polymorphic names
		foo :: proc($N: $I, $T: typeid) -> (res: [N]T) {
			// `N` is the constant value passed
			// `I` is the type of N
			// `T` is the type passed
			fmt.printf("Generating an array of type %v from the value %v of type %v\n",
					   typeid_of(type_of(res)), N, typeid_of(I));
			for i in 0..<N {
				res[i] = T(i*i);
			}
			return;
		}

		T :: int;
		array := foo(4, T);
		for v, i in array {
			assert(v == T(i*i));
		}

		// Matrix multiplication
		mul :: proc(a: [$M][$N]$T, b: [N][$P]T) -> (c: [M][P]T) {
			for i in 0..<M {
				for j in 0..<P {
					for k in 0..<N {
						c[i][j] += a[i][k] * b[k][j];
					}
				}
			}
			return;
		}

		x := [2][3]f32{
			{1, 2, 3},
			{3, 2, 1},
		};
		y := [3][2]f32{
			{0, 8},
			{6, 2},
			{8, 4},
		};
		z := mul(x, y);
		assert(z == {{36, 24}, {20, 32}});
	}
}


prefix_table := [?]string{
	"White",
	"Red",
	"Green",
	"Blue",
	"Octarine",
	"Black",
};

threading_example :: proc() {
	if ODIN_OS == "darwin" {
		// TODO: Fix threads on darwin/macOS
		return;
	}

	fmt.println("\n# threading_example");

	{ // Basic Threads
		fmt.println("\n## Basic Threads");
			worker_proc :: proc(t: ^thread.Thread) {
			for iteration in 1..=5 {
				fmt.printf("Thread %d is on iteration %d\n", t.user_index, iteration);
				fmt.printf("`%s`: iteration %d\n", prefix_table[t.user_index], iteration);
				time.sleep(1 * time.Millisecond);
			}
		}

		threads := make([dynamic]^thread.Thread, 0, len(prefix_table));
		defer delete(threads);

		for in prefix_table {
			if t := thread.create(worker_proc); t != nil {
				t.init_context = context;
				t.user_index = len(threads);
				append(&threads, t);
				thread.start(t);
			}
		}

		for len(threads) > 0 {
			for i := 0; i < len(threads); /**/ {
				if t := threads[i]; thread.is_done(t) {
					fmt.printf("Thread %d is done\n", t.user_index);
					thread.destroy(t);

					ordered_remove(&threads, i);
				} else {
					i += 1;
				}
			}
		}
	}

	{ // Thread Pool
		fmt.println("\n## Thread Pool");
		task_proc :: proc(t: ^thread.Task) {
			index := t.user_index % len(prefix_table);
			for iteration in 1..=5 {
				fmt.printf("Worker Task %d is on iteration %d\n", t.user_index, iteration);
				fmt.printf("`%s`: iteration %d\n", prefix_table[index], iteration);
				time.sleep(1 * time.Millisecond);
			}
		}

		pool: thread.Pool;
		thread.pool_init(pool=&pool, thread_count=3);
		defer thread.pool_destroy(&pool);


		for i in 0..<30 {
			thread.pool_add_task(pool=&pool, procedure=task_proc, data=nil, user_index=i);
		}

		thread.pool_start(&pool);
		thread.pool_wait_and_process(&pool);
	}
}


array_programming :: proc() {
	fmt.println("\n# array programming");
	{
		a := [3]f32{1, 2, 3};
		b := [3]f32{5, 6, 7};
		c := a * b;
		d := a + b;
		e := 1 +  (c - d) / 2;
		fmt.printf("%.1f\n", e); // [0.5, 3.0, 6.5]
	}

	{
		a := [3]f32{1, 2, 3};
		b := swizzle(a, 2, 1, 0);
		assert(b == [3]f32{3, 2, 1});

		c := swizzle(a, 0, 0);
		assert(c == [2]f32{1, 1});
		assert(c == 1);
	}

	{
		Vector3 :: distinct [3]f32;
		a := Vector3{1, 2, 3};
		b := Vector3{5, 6, 7};
		c := (a * b)/2 + 1;
		d := c.x + c.y + c.z;
		fmt.printf("%.1f\n", d); // 22.0

		cross :: proc(a, b: Vector3) -> Vector3 {
			i := swizzle(a, 1, 2, 0) * swizzle(b, 2, 0, 1);
			j := swizzle(a, 2, 0, 1) * swizzle(b, 1, 2, 0);
			return i - j;
		}

		cross_shorter :: proc(a, b: Vector3) -> Vector3 {
			i := a.yzx * b.zxy;
			j := a.zxy * b.yzx;
			return i - j;
		}

		blah :: proc(a: Vector3) -> f32 {
			return a.x + a.y + a.z;
		}

		x := cross(a, b);
		fmt.println(x);
		fmt.println(blah(x));
	}
}

map_type :: proc() {
	fmt.println("\n# map type");

	m := make(map[string]int);
	defer delete(m);

	m["Bob"] = 2;
	m["Ted"] = 5;
	fmt.println(m["Bob"]);

	delete_key(&m, "Ted");

	// If an element of a key does not exist, the zero value of the
	// element will be returned. To check to see if an element exists
	// can be done in two ways:
	elem, ok := m["Bob"];
	exists := "Bob" in m;
	_, _ = elem, ok;
	_ = exists;
}

implicit_selector_expression :: proc() {
	fmt.println("\n# implicit selector expression");

	Foo :: enum {A, B, C};

	f: Foo;
	f = Foo.A;
	f = .A;

	BAR :: bit_set[Foo]{.B, .C};

	switch f {
	case .A:
		fmt.println("HITHER");
	case .B:
		fmt.println("NEVER");
	case .C:
		fmt.println("FOREVER");
	}

	my_map := make(map[Foo]int);
	defer delete(my_map);

	my_map[.A] = 123;
	my_map[Foo.B] = 345;

	fmt.println(my_map[.A] + my_map[Foo.B] + my_map[.C]);
}


partial_switch :: proc() {
	fmt.println("\n# partial_switch");
	{ // enum
		Foo :: enum {
			A,
			B,
			C,
			D,
		};

		f := Foo.A;
		switch f {
		case .A: fmt.println("A");
		case .B: fmt.println("B");
		case .C: fmt.println("C");
		case .D: fmt.println("D");
		case:    fmt.println("?");
		}

		#partial switch f {
		case .A: fmt.println("A");
		case .D: fmt.println("D");
		}
	}
	{ // union
		Foo :: union {int, bool};
		f: Foo = 123;
		switch in f {
		case int:  fmt.println("int");
		case bool: fmt.println("bool");
		case:
		}

		#partial switch in f {
		case bool: fmt.println("bool");
		}
	}
}

cstring_example :: proc() {
	fmt.println("\n# cstring_example");

	W :: "Hellope";
	X :: cstring(W);
	Y :: string(X);

	w := W;
	_ = w;
	x: cstring = X;
	y: string = Y;
	z := string(x);
	fmt.println(x, y, z);
	fmt.println(len(x), len(y), len(z));
	fmt.println(len(W), len(X), len(Y));
	// IMPORTANT NOTE for cstring variables
	// len(cstring) is O(N)
	// cast(string)cstring is O(N)
}

bit_set_type :: proc() {
	fmt.println("\n# bit_set type");

	{
		Day :: enum {
			Sunday,
			Monday,
			Tuesday,
			Wednesday,
			Thursday,
			Friday,
			Saturday,
		};

		Days :: distinct bit_set[Day];
		WEEKEND :: Days{.Sunday, .Saturday};

		d: Days;
		d = {.Sunday, .Monday};
		e := d + WEEKEND;
		e += {.Monday};
		fmt.println(d, e);

		ok := .Saturday in e; // `in` is only allowed for `map` and `bit_set` types
		fmt.println(ok);
		if .Saturday in e {
			fmt.println("Saturday in", e);
		}
		X :: .Saturday in WEEKEND; // Constant evaluation
		fmt.println(X);
		fmt.println("Cardinality:", card(e));
	}
	{
		x: bit_set['A'..='Z'];
		#assert(size_of(x) == size_of(u32));
		y: bit_set[0..=8; u16];
		fmt.println(typeid_of(type_of(x))); // bit_set[A..=Z]
		fmt.println(typeid_of(type_of(y))); // bit_set[0..=8; u16]

		x += {'F'};
		assert('F' in x);
		x -= {'F'};
		assert('F' not_in x);

		y += {1, 4, 2};
		assert(2 in y);
	}
	{
		Letters :: bit_set['A'..='Z'];
		a := Letters{'A', 'B'};
		b := Letters{'A', 'B', 'C', 'D', 'F'};
		c := Letters{'A', 'B'};

		assert(a <= b); // 'a' is a subset of 'b'
		assert(b >= a); // 'b' is a superset of 'a'
		assert(a < b);  // 'a' is a strict subset of 'b'
		assert(b > a);  // 'b' is a strict superset of 'a'

		assert(!(a < c)); // 'a' is a not strict subset of 'c'
		assert(!(c > a)); // 'c' is a not strict superset of 'a'
	}
}

deferred_procedure_associations :: proc() {
	fmt.println("\n# deferred procedure associations");

	@(deferred_out=closure)
	open :: proc(s: string) -> bool {
		fmt.println(s);
		return true;
	}

	closure :: proc(ok: bool) {
		fmt.println("Goodbye?", ok);
	}

	if open("Welcome") {
		fmt.println("Something in the middle, mate.");
	}
}

reflection :: proc() {
	fmt.println("\n# reflection");

	Foo :: struct {
		x: int    `tag1`,
		y: string `json:"y_field"`,
		z: bool, // no tag
	};

	id := typeid_of(Foo);
	names := reflect.struct_field_names(id);
	types := reflect.struct_field_types(id);
	tags  := reflect.struct_field_tags(id);

	assert(len(names) == len(types) && len(names) == len(tags));

	fmt.println("Foo :: struct {");
	for tag, i in tags {
		name, type := names[i], types[i];
		if tag != "" {
			fmt.printf("\t%s: %T `%s`,\n", name, type, tag);
		} else {
			fmt.printf("\t%s: %T,\n", name, type);
		}
	}
	fmt.println("}");


	for tag, i in tags {
		if val, ok := reflect.struct_tag_lookup(tag, "json"); ok {
			fmt.printf("json: %s -> %s\n", names[i], val);
		}
	}
}

quaternions :: proc() {
	// Not just an April Fool's Joke any more, but a fully working thing!
	fmt.println("\n# quaternions");

	{ // Quaternion operations
		q := 1 + 2i + 3j + 4k;
		r := quaternion(5, 6, 7, 8);
		t := q * r;
		fmt.printf("(%v) * (%v) = %v\n", q, r, t);
		v := q / r;
		fmt.printf("(%v) / (%v) = %v\n", q, r, v);
		u := q + r;
		fmt.printf("(%v) + (%v) = %v\n", q, r, u);
		s := q - r;
		fmt.printf("(%v) - (%v) = %v\n", q, r, s);
	}
	{ // The quaternion types
		q128: quaternion128; // 4xf32
		q256: quaternion256; // 4xf64
		q128 = quaternion(1, 0, 0, 0);
		q256 = 1; // quaternion(1, 0, 0, 0);
	}
	{ // Built-in procedures
		q := 1 + 2i + 3j + 4k;
		fmt.println("q =", q);
		fmt.println("real(q) =", real(q));
		fmt.println("imag(q) =", imag(q));
		fmt.println("jmag(q) =", jmag(q));
		fmt.println("kmag(q) =", kmag(q));
		fmt.println("conj(q) =", conj(q));
		fmt.println("abs(q)  =", abs(q));
	}
	{ // Conversion of a complex type to a quaternion type
		c := 1 + 2i;
		q := quaternion256(c);
		fmt.println(c);
		fmt.println(q);
	}
	{ // Memory layout of Quaternions
		q := 1 + 2i + 3j + 4k;
		a := transmute([4]f64)q;
		fmt.println("Quaternion memory layout: xyzw/(ijkr)");
		fmt.println(q); // 1.000+2.000i+3.000j+4.000k
		fmt.println(a); // [2.000, 3.000, 4.000, 1.000]
	}
}

unroll_for_statement :: proc() {
	fmt.println("\n#'#unroll for' statements");

	// '#unroll for' works the same as if the 'inline' prefix did not
	// exist but these ranged loops are explicitly unrolled which can
	// be very very useful for certain optimizations

	fmt.println("Ranges");
	#unroll for x, i in 1..<4 {
		fmt.println(x, i);
	}

	fmt.println("Strings");
	#unroll for r, i in "Hello, 世界" {
		fmt.println(r, i);
	}

	fmt.println("Arrays");
	#unroll for elem, idx in ([4]int{1, 4, 9, 16}) {
		fmt.println(elem, idx);
	}


	Foo_Enum :: enum {
		A = 1,
		B,
		C = 6,
		D,
	};
	fmt.println("Enum types");
	#unroll for elem, idx in Foo_Enum {
		fmt.println(elem, idx);
	}
}

where_clauses :: proc() {
	fmt.println("\n#procedure 'where' clauses");

	{ // Sanity checks
		simple_sanity_check :: proc(x: [2]int)
			where len(x) > 1,
				  type_of(x) == [2]int {
			fmt.println(x);
		}
	}
	{ // Parametric polymorphism checks
		cross_2d :: proc(a, b: $T/[2]$E) -> E
			where intrinsics.type_is_numeric(E) {
			return a.x*b.y - a.y*b.x;
		}
		cross_3d :: proc(a, b: $T/[3]$E) -> T
			where intrinsics.type_is_numeric(E) {
			x := a.y*b.z - a.z*b.y;
			y := a.z*b.x - a.x*b.z;
			z := a.x*b.y - a.y*b.z;
			return T{x, y, z};
		}

		a := [2]int{1, 2};
		b := [2]int{5, -3};
		fmt.println(cross_2d(a, b));

		x := [3]f32{1, 4, 9};
		y := [3]f32{-5, 0, 3};
		fmt.println(cross_3d(x, y));

		// Failure case
		// i := [2]bool{true, false};
		// j := [2]bool{false, true};
		// fmt.println(cross_2d(i, j));

	}

	{ // Procedure groups usage
		foo :: proc(x: [$N]int) -> bool
			where N > 2 {
			fmt.println(#procedure, "was called with the parameter", x);
			return true;
		}

		bar :: proc(x: [$N]int) -> bool
			where 0 < N,
				  N <= 2 {
			fmt.println(#procedure, "was called with the parameter", x);
			return false;
		}

		baz :: proc{foo, bar};

		x := [3]int{1, 2, 3};
		y := [2]int{4, 9};
		ok_x := baz(x);
		ok_y := baz(y);
		assert(ok_x == true);
		assert(ok_y == false);
	}

	{ // Record types
		Foo :: struct($T: typeid, $N: int)
			where intrinsics.type_is_integer(T),
				  N > 2 {
			x: [N]T,
			y: [N-2]T,
		};

		T :: i32;
		N :: 5;
		f: Foo(T, N);
		#assert(size_of(f) == (N+N-2)*size_of(T));
	}
}


when ODIN_OS == "windows" {
	foreign import kernel32 "system:kernel32.lib"
}

foreign_system :: proc() {
	fmt.println("\n#foreign system");
	when ODIN_OS == "windows" {
		// It is sometimes necessarily to interface with foreign code,
		// such as a C library. In Odin, this is achieved through the
		// foreign system. You can “import” a library into the code
		// using the same semantics as a normal import declaration.

		// This foreign import declaration will create a
		// “foreign import name” which can then be used to associate
		// entities within a foreign block.

		foreign kernel32 {
			ExitProcess :: proc "stdcall" (exit_code: u32) ---
		}

		// Foreign procedure declarations have the cdecl/c calling
		// convention by default unless specified otherwise. Due to
		// foreign procedures do not have a body declared within this
		// code, you need append the --- symbol to the end to distinguish
		// it as a procedure literal without a body and not a procedure type.

		// The attributes system can be used to change specific properties
		// of entities declared within a block:

		@(default_calling_convention = "std")
		foreign kernel32 {
			@(link_name="GetLastError") get_last_error :: proc() -> i32 ---
		}

		// Example using the link_prefix attribute
		@(default_calling_convention = "std")
		@(link_prefix = "Get")
		foreign kernel32 {
			LastError :: proc() -> i32 ---
		}
	}
}

ranged_fields_for_array_compound_literals :: proc() {
	fmt.println("\n#ranged fields for array compound literals");
	{ // Normal Array Literal
		foo := [?]int{1, 4, 9, 16};
		fmt.println(foo);
	}
	{ // Indexed
		foo := [?]int{
			3 = 16,
			1 = 4,
			2 = 9,
			0 = 1,
		};
		fmt.println(foo);
	}
	{ // Ranges
		i := 2;
		foo := [?]int {
			0 = 123,
			5..=9 = 54,
			10..<16 = i*3 + (i-1)*2,
		};
		#assert(len(foo) == 16);
		fmt.println(foo); // [123, 0, 0, 0, 0, 54, 54, 54, 54, 54, 8, 8, 8, 8, 8]
	}
	{ // Slice and Dynamic Array support
		i := 2;
		foo_slice := []int {
			0 = 123,
			5..=9 = 54,
			10..<16 = i*3 + (i-1)*2,
		};
		assert(len(foo_slice) == 16);
		fmt.println(foo_slice); // [123, 0, 0, 0, 0, 54, 54, 54, 54, 54, 8, 8, 8, 8, 8]

		foo_dynamic_array := [dynamic]int {
			0 = 123,
			5..=9 = 54,
			10..<16 = i*3 + (i-1)*2,
		};
		assert(len(foo_dynamic_array) == 16);
		fmt.println(foo_dynamic_array); // [123, 0, 0, 0, 0, 54, 54, 54, 54, 54, 8, 8, 8, 8, 8]
	}
}

deprecated_attribute :: proc() {
	@(deprecated="Use foo_v2 instead")
	foo_v1 :: proc(x: int) {
		fmt.println("foo_v1");
	}
	foo_v2 :: proc(x: int) {
		fmt.println("foo_v2");
	}

	// NOTE: Uncomment to see the warning messages
	// foo_v1(1);
}

range_statements_with_multiple_return_values :: proc() {
	// IMPORTANT NOTE(bill, 2019-11-02): This feature is subject to be changed/removed
	fmt.println("\n#range statements with multiple return values");
	My_Iterator :: struct {
		index: int,
		data:  []i32,
	};
	make_my_iterator :: proc(data: []i32) -> My_Iterator {
		return My_Iterator{data = data};
	}
	my_iterator :: proc(it: ^My_Iterator) -> (val: i32, idx: int, cond: bool) {
		if cond = it.index < len(it.data); cond {
			val = it.data[it.index];
			idx = it.index;
			it.index += 1;
		}
		return;
	}

	data := make([]i32, 6);
	for _, i in data {
		data[i] = i32(i*i);
	}

	{
		it := make_my_iterator(data);
		for val in my_iterator(&it) {
			fmt.println(val);
		}
	}
	{
		it := make_my_iterator(data);
		for val, idx in my_iterator(&it) {
			fmt.println(val, idx);
		}
	}
	{
		it := make_my_iterator(data);
		for {
			val, _, cond := my_iterator(&it);
			if !cond {
				break;
			}
			fmt.println(val);
		}
	}
}


soa_struct_layout :: proc() {
	fmt.println("\n#SOA Struct Layout");

	{
		Vector3 :: struct {x, y, z: f32};

		N :: 2;
		v_aos: [N]Vector3;
		v_aos[0].x = 1;
		v_aos[0].y = 4;
		v_aos[0].z = 9;

		fmt.println(len(v_aos));
		fmt.println(v_aos[0]);
		fmt.println(v_aos[0].x);
		fmt.println(&v_aos[0].x);

		v_aos[1] = {0, 3, 4};
		v_aos[1].x = 2;
		fmt.println(v_aos[1]);
		fmt.println(v_aos);

		v_soa: #soa[N]Vector3;

		v_soa[0].x = 1;
		v_soa[0].y = 4;
		v_soa[0].z = 9;


		// Same syntax as AOS and treat as if it was an array
		fmt.println(len(v_soa));
		fmt.println(v_soa[0]);
		fmt.println(v_soa[0].x);
		fmt.println(&v_soa[0].x);
		v_soa[1] = {0, 3, 4};
		v_soa[1].x = 2;
		fmt.println(v_soa[1]);

		// Can use SOA syntax if necessary
		v_soa.x[0] = 1;
		v_soa.y[0] = 4;
		v_soa.z[0] = 9;
		fmt.println(v_soa.x[0]);

		// Same pointer addresses with both syntaxes
		assert(&v_soa[0].x == &v_soa.x[0]);


		// Same fmt printing
		fmt.println(v_aos);
		fmt.println(v_soa);
	}
	{
		// Works with arrays of length <= 4 which have the implicit fields xyzw/rgba
		Vector3 :: distinct [3]f32;

		N :: 2;
		v_aos: [N]Vector3;
		v_aos[0].x = 1;
		v_aos[0].y = 4;
		v_aos[0].z = 9;

		v_soa: #soa[N]Vector3;

		v_soa[0].x = 1;
		v_soa[0].y = 4;
		v_soa[0].z = 9;
	}
	{
		// SOA Slices
		// Vector3 :: struct {x, y, z: f32};
		Vector3 :: struct {x: i8, y: i16, z: f32};

		N :: 3;
		v: #soa[N]Vector3;
		v[0].x = 1;
		v[0].y = 4;
		v[0].z = 9;

		s: #soa[]Vector3;
		s = v[:];
		assert(len(s) == N);
		fmt.println(s);
		fmt.println(s[0].x);

		a := s[1:2];
		assert(len(a) == 1);
		fmt.println(a);

		d: #soa[dynamic]Vector3;

		append_soa(&d, Vector3{1, 2, 3}, Vector3{4, 5, 9}, Vector3{-4, -4, 3});
		fmt.println(d);
		fmt.println(len(d));
		fmt.println(cap(d));
		fmt.println(d[:]);
	}
	{ // soa_zip and soa_unzip
		fmt.println("\nsoa_zip and soa_unzip");

		x := []i32{1, 3, 9};
		y := []f32{2, 4, 16};
		z := []b32{true, false, true};

		// produce an #soa slice the normal slices passed
		s := soa_zip(a=x, b=y, c=z);

		// iterate over the #soa slice
		for v, i in s {
			fmt.println(v, i); // exactly the same as s[i]
			// NOTE: 'v' is NOT a temporary value but has a specialized addressing mode
			// which means that when accessing v.a etc, it does the correct transformation
			// internally:
			//         s[i].a === s.a[i]
			fmt.println(v.a, v.b, v.c);
		}

		// Recover the slices from the #soa slice
		a, b, c := soa_unzip(s);
		fmt.println(a, b, c);
	}
}

constant_literal_expressions :: proc() {
	fmt.println("\n#constant literal expressions");

	Bar :: struct {x, y: f32};
	Foo :: struct {a, b: int, using c: Bar};

	FOO_CONST :: Foo{b = 2, a = 1, c = {3, 4}};


	fmt.println(FOO_CONST.a);
	fmt.println(FOO_CONST.b);
	fmt.println(FOO_CONST.c);
	fmt.println(FOO_CONST.c.x);
	fmt.println(FOO_CONST.c.y);
	fmt.println(FOO_CONST.x); // using works as expected
	fmt.println(FOO_CONST.y);

	fmt.println("-------");

	ARRAY_CONST :: [3]int{1 = 4, 2 = 9, 0 = 1};

	fmt.println(ARRAY_CONST[0]);
	fmt.println(ARRAY_CONST[1]);
	fmt.println(ARRAY_CONST[2]);

	fmt.println("-------");

	FOO_ARRAY_DEFAULTS :: [3]Foo{{}, {}, {}};
	fmt.println(FOO_ARRAY_DEFAULTS[2].x);

	fmt.println("-------");

	Baz :: enum{A=5, B, C, D};
	ENUM_ARRAY_CONST :: [Baz]int{.A ..= .C = 1, .D = 16};

	fmt.println(ENUM_ARRAY_CONST[.A]);
	fmt.println(ENUM_ARRAY_CONST[.B]);
	fmt.println(ENUM_ARRAY_CONST[.C]);
	fmt.println(ENUM_ARRAY_CONST[.D]);

	fmt.println("-------");

	Partial_Baz :: enum{A=5, B, C, D=16};
	#assert(len(Partial_Baz) < len(#partial [Partial_Baz]int));
	PARTIAL_ENUM_ARRAY_CONST :: #partial [Partial_Baz]int{.A ..= .C = 1, .D = 16};

	fmt.println(PARTIAL_ENUM_ARRAY_CONST[.A]);
	fmt.println(PARTIAL_ENUM_ARRAY_CONST[.B]);
	fmt.println(PARTIAL_ENUM_ARRAY_CONST[.C]);
	fmt.println(PARTIAL_ENUM_ARRAY_CONST[.D]);

	fmt.println("-------");


	STRING_CONST :: "Hellope!";

	fmt.println(STRING_CONST[0]);
	fmt.println(STRING_CONST[2]);
	fmt.println(STRING_CONST[3]);

	fmt.println(STRING_CONST[0:5]);
	fmt.println(STRING_CONST[3:][:4]);
}

union_maybe :: proc() {
	fmt.println("\n#union #maybe");

	// NOTE: This is already built-in, and this is just a reimplementation to explain the behaviour
	Maybe :: union($T: typeid) #maybe {T};

	i: Maybe(u8);
	p: Maybe(^u8); // No tag is stored for pointers, nil is the sentinel value

	#assert(size_of(i) == size_of(u8) + size_of(u8));
	#assert(size_of(p) == size_of(^u8));

	i = 123;
	x := i.?;
	y, y_ok := p.?;
	p = &x;
	z, z_ok := p.?;

	fmt.println(i, p);
	fmt.println(x, &x);
	fmt.println(y, y_ok);
	fmt.println(z, z_ok);
}

dummy_procedure :: proc() {
	fmt.println("dummy_procedure");
}

explicit_context_definition :: proc "c" () {
	// Try commenting the following statement out below
	context = runtime.default_context();

	fmt.println("\n#explicit context definition");
	dummy_procedure();
}

relative_data_types :: proc() {
	fmt.println("\n#relative data types");

	x: int = 123;
	ptr: #relative(i16) ^int;
	ptr = &x;
	fmt.println(ptr^);

	arr := [3]int{1, 2, 3};
	s := arr[:];
	rel_slice: #relative(i16) []int;
	rel_slice = s;
	fmt.println(rel_slice);
	fmt.println(rel_slice[:]);
	fmt.println(rel_slice[1]);
}

or_else_operator :: proc() {
	fmt.println("\n#'or_else'");
	// IMPORTANT NOTE: 'or_else' is an experimental feature and subject to change/removal
	{
		m: map[string]int;
		i: int;
		ok: bool;

		if i, ok = m["hellope"]; !ok {
			i = 123;
		}
		// The above can be mapped to 'or_else'
		i = m["hellope"] or_else 123;

		assert(i == 123);
	}
	{
		// 'or_else' can be used with type assertions too, as they
		// have optional ok semantics
		v: union{int, f64};
		i: int;
		i = v.(int) or_else  123;
		i = v.? or_else 123; // Type inference magic
		assert(i == 123);

		m: Maybe(int);
		i = m.? or_else 456;
		assert(i == 456);
	}
}

or_return_operator :: proc() {
	fmt.println("\n#'or_return'");
	// IMPORTANT NOTE: 'or_return' is an experimental feature and subject to change/removal
	//
	// The concept of 'or_return' will work by popping off the end value in a multiple
	// valued expression and checking whether it was not 'nil' or 'false', and if so,
	// set the end return value to value if possible. If the procedure only has one
	// return value, it will do a simple return. If the procedure had multiple return
	// values, 'or_return' will require that all parameters be named so that the end
	// value could be assigned to by name and then an empty return could be called.

	Error :: enum {
		None,
		Something_Bad,
		Something_Worse,
		The_Worst,
		Your_Mum,
	};

	caller_1 :: proc() -> Error {
		return .None;
	}

	caller_2 :: proc() -> (int, Error) {
		return 123, .None;
	}
	caller_3 :: proc() -> (int, int, Error) {
		return 123, 345, .None;
	}

	foo_1 :: proc() -> Error {
		// This can be a common idiom in many code bases
		n0, err := caller_2();
		if err != nil {
			return err;
		}

		// The above idiom can be transformed into the following
		n1 := caller_2() or_return;


		// And if the expression is 1-valued, it can be used like this
		caller_1() or_return;
		// which is functionally equivalent to
		if err1 := caller_1(); err1 != nil {
			return err1;
		}

		// Multiple return values still work with 'or_return' as it only
		// pops off the end value in the multi-valued expression
		n0, n1 = caller_3() or_return;

		return .None;
	}
	foo_2 :: proc() -> (n: int, err: Error) {
		// It is more common that your procedure turns multiple values
		// If 'or_return' is used within a procedure multiple parameters (2+),
		// then all the parameters must be named so that the remaining parameters
		// so that a bare 'return' statement can be used

		// This can be a common idiom in many code bases
		x: int;
		x, err = caller_2();
		if err != nil {
			return;
		}

		// The above idiom can be transformed into the following
		y := caller_2() or_return;
		_ = y;

		// And if the expression is 1-valued, it can be used like this
		caller_1() or_return;

		// which is functionally equivalent to
		if err1 := caller_1(); err1 != nil {
			err = err1;
			return;
		}

		// If using a non-bare 'return' statement is required, setting the return values
		// using the normal idiom is a better choice and clearer to read.
		if z, zerr := caller_2(); zerr != nil {
			return -345 * z, zerr;
		}

		// If the other return values need to be set depending on what the end value is,
		// the 'defer if' idiom is can be used
		defer if err != nil {
			n = -1;
		}

		n = 123;
		return;
	}

	foo_1();
	foo_2();
}


main :: proc() {
	when true {
		the_basics();
		control_flow();
		named_proc_return_parameters();
		explicit_procedure_overloading();
		struct_type();
		union_type();
		using_statement();
		implicit_context_system();
		parametric_polymorphism();
		array_programming();
		map_type();
		implicit_selector_expression();
		partial_switch();
		cstring_example();
		bit_set_type();
		deferred_procedure_associations();
		reflection();
		quaternions();
		unroll_for_statement();
		where_clauses();
		foreign_system();
		ranged_fields_for_array_compound_literals();
		deprecated_attribute();
		range_statements_with_multiple_return_values();
		threading_example();
		soa_struct_layout();
		constant_literal_expressions();
		union_maybe();
		explicit_context_definition();
		relative_data_types();
		or_else_operator();
		or_return_operator();
	}
}