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README.md

cx logo

CX Programming Language

Build Status Build status

CX is a general purpose, interpreted and compiled programming language, with a very strict type system and a syntax similar to Golang's. CX provides a new programming paradigm based on the concept of affordances.

Table of Contents

CX Programming Language

CX is a general purpose, interpreted and compiled programming language, with a very strict type system and a syntax similar to Golang's. CX provides a new programming paradigm based on the concept of affordances, where the user can ask the programming language at runtime what can be done with a CX object (functions, expressions, packages, etc.), and interactively or automatically choose one of the affordances to be applied. This paradigm has the main objective of providing an additional security layer for decentralized, blockchain-based applications, but can also be used for general purpose programming.

In the following sections, the reader can find a short tutorial on how to use the main features of the language. In previous versions of this README file, the tutorial was written in a book-ish style and was targetted to a beginner audience. We're going to be making a transition from that style to a more technical style, without falling into a pure documentation style. The reason behind this is that a CX book is going to be published, which is targetted to a more beginner audience. Thus, this README now has the purpose of quickly demonstrating the capabilities of the language, how to install it, etc. You can find the book source code and its releases in its CX book Github repository.

This tutorial/documentation is divided into four parts, which can broadly be described as introduction, syntax, runtime and native functions. The first section presents general information about the language, such as how to install it, the development roadmap, etc. The second and third sections are more tutorial-ish, where the reader can find information about the core language, i.e. how your program needs to look so it's considered a valid CX program (syntax), and how your CX program is going to be executing (runtime). The last section follows a more documentation style, where each of the native functions of the language is presented, along with an example.

Feel free to create an issue requesting a better explanation of a feature.

Strict Type System

As mentioned in the description of the language, CX has a strict type system. Most of the native functions in CX are associated to a single type signature. For example, str.print seen in the "Hello, World!" program only accepts strings as its input argument. There are versions of print for each of the primitive types, such as i32.print, f32.print, etc. The purpose of this is to

There are native functions in CX (the functions in the core language) associated to

CX Book

You can find the book source code and its releases in its CX book Github repository.

CX Projects, Libraries and other Resources

CX Chains:

CX Examples:

CX Libraries:

CX Video Games:

Miscellaneous:

CX Roadmap

CX Roadmap

CX Chains (CX + Skycoin Blockchain)

CX Chains are Skycoin's solution for the creation of blockchain-based programs. You can read more about them in the CX wiki for the latest release or in documentation/BLOCKCHAIN.md for the develop branch of CX (the bleeding edge version of CX).

Changelog

Check out the latest additions and bug fixes in the changelog.

Installation

Binary Releases

This repository provides new binary releases of the language every week. Check this link and download the appropriate binary release for your platfrom: https://github.com/skycoin/cx/releases

More platforms will be added in the future.

CX has been successfully installed and tested in recent versions of Linux (Ubuntu), MacOS X and Windows. Nevertheless, if you run into any problems, please create an issue and we'll try to solve the problem as soon as possible.

Once you have downloaded and de-compressed the binary release file, you should place it somewhere in your operating system's $PATH environment variable (or similar). The purpose of this is to have cx globally accessible when using the terminal.

If you don't want to have it globally accessible, you can always try out CX locally, inside the directory where you have the binary file.

MacOS Homebrew Install

The simplest way to install CX on MacOS is to use the Homebrew package manager to install the prebuilt binary release. If you do not already have Homebrew installed, please visit the Homebrew website for installation instructions.

Once Homebrew is installed, use the following commands to setup the Tap and then install CX.

brew tap skycoin/homebrew-skycoin
brew install skycoin-cx

To update use the following command:

brew update skycoin-cx

Compiling from Source

If a binary release is not currently available for your platfrom or if you want to have a nightly build of CX, you'll have to compile from source. If you're not familiarized with Go, Git, your OS's terminal or your OS's package manager (to name a few), we strongly recommend you to try out a binary release. If you find any bugs or problems with the binary release, submit an issue here: https://github.com/skycoin/cx/issues, and we'll fix it for the next release.

Installing Go

CX supports go1.10+.

Go 1.10+ installation/setup

Compiling CX on *nix

Download CX's repository using Go:

go get github.com/skycoin/cx/cx/...

Navigate to CX's repository, and run:

make install

You should test your installation by running:

make test

If you intend to develop games with CX, then run:

make test-full

Compiling CX on Windows

An installation script is also provided for Windows named cx-setup.bat. You can compile CX on Windows by running:

cx-setup.bat

You should test your installation by running:

cx tests\main.cx ++wdir=tests ++disable-tests=issue

Updating CX

You can update your CX installation by running:

make install

Or on Windows:

cx-setup.bat

Running CX

CX REPL

Once CX has been successfully installed, running cx should print this in your terminal:

CX 0.5.13
More information about CX is available at http://cx.skycoin.net/ and https://github.com/skycoin/cx/
:func main {...
	*

This is the CX REPL (read-eval-print loop), where you can debug and modify CX programs. The CX REPL starts with a barebones CX structure (a main package and a main function) that you can use to start building a program.

Let's create a small program to test the REPL. First, write str.print("Testing the REPL") after the *, and press enter. After pressing enter you'll see the message "Testing the REPL" on the screen. If you then write :dp (short for :dProgram or debug program), you should get the current program AST printed:

Program
0.- Package: main
	Functions
		0.- Function: main () ()
			0.- Expression: str.print("" str)
		1.- Function: *init () ()

As we can see, we have a main package, a main function, and we have a single expression: str.print("Testing the REPL").

Let's now create a new function. In order to do this, we first need to leave the main function. At this moment, any expression (or function call) that we add to our program is going to be added to main. To exit a function declaration, press Ctrl+D. The prompt (*) should have changed indentation, and the REPL now shouldn't print :func main {... above the prompt:

:func main {...
	*
*

Now, let's enter a function prototype (an empty function which only specifies the name, the inputs and the outputs):

* func sum (num1 i32, num2 i32) (num3 i32) {}
*

You can check that the function was indeed added by issuing a :dp command. If we want to add expressions to sum, we have to select it:

* :func sum

:func sum {...
	*

Notice that there's a semicolon before func sum. Now we can add an expression to it:

:func sum {...
	* num3 = num1 + num2

Now, exit sum and select main with the command :func main. Let's add a call to sum and print the value that it returns when giving the arguments 10 and 20:

:func main {...
	* i32.print(sum(10, 20))
30

Running CX Programs

To run a CX program, you have to type, for example, cx the-program.cx. Let's try to run some examples from the examples directory in this repository. In a terminal, type this:

cd $GOPATH/src/github.com/skycoin/cx/
cx examples/hello-world.cx

This should print Hello World! in the terminal. Now try running cx examples/opengl/game.cx.

Other Options

If you write cx --help or cx -h, you should see a text describing CX's usage, options and more.

Some interesting options are:

  • --base which generates a CX program's assembly code (in Go)
  • --compile which generates an executable file
  • --repl which loads the program and makes CX run in REPL mode (useful for debugging a program)
  • --web which starts CX as a RESTful web service (you can send code to be evaluated to this endpoint: http://127.0.0.1:5336/eval)

Hello World

Do you want to know how CX looks? This is how you print "Hello, World!" in a terminal:

package main

func main () {
    str.print("Hello, World!")
}

Every CX program must have at least a main package, and a main function. As mentioned before, CX has a strict type system, where functions can only be associated with a single type signature. As a consequence, if we want to print a string, as in the example above, we have to call str's print function, where str is a package containing string related functions.

However, there are some exceptions, mainly to functions where it makes sense to have a generalized type signature. For example, the len function accepts arrays of any type as its argument, instead of having []i32.len() or [][]str.len(). Another example is sprintf, which is used to construct a string using a format string and a series of arguments of any type.

Syntax

In this section, we're going to have a look at how a CX program looks like. Basically, the following sections are not going to discuss about the logic behind the various CX constructs, i.e. how they behave; we're only going to see how they look like.

Comments

Some of the code snippets that follow have comments in them, i.e., blocks of text that are not actually "run" by the CX compiler or interpreter. Just like in C, Golang and many other programming languages, single line comments are created by placing double slashes (//) before the text being commented. For example:

// Example of adding two 32 bit integers in CX

i32.add(3, 4)       // This will be ignored

// End of the program

Mult-line comments are opened by writing slash-asterisk (/*), and are closed by writing asterisk-slash (*/).

/* This code won't be executed
str.print("Hello world!")
*/

Declarations

A declaration refers to a named element in a program's structure, which are described using other constructs, such as expressions and other statements. For example: a function can be referred by its name and it's constructed by expressions and local variable declarations.

Allowed Names

Any name that satisfies the PCRE regular expression [_a-zA-Z][_a-zA-Z0-9]* is allowed as an identifier for a declared element. In other words, an identifier can start with an underscore (_) or any lowercase or uppercase letter, and can be followed by 0 or more underscores or lowercase or uppercase letters, and any number from 0 to 9.

Strict Type System

One of CX's goals is to provide a very strict type system. The purpose of this is to reduce runtime errors as much as possible. In order to achieve this goal, many of CX's native functions are constrained to a single type signature. For example, if you want to add two 32-bit integers, you'd need to use i32.add. In contrast, if you want to add two 64-bit integers, you'd use i64.add. These functions can help the programmer to ensure that a particular data type is being received or sent during a process.

If the programmer doesn't want to use those type-specific functions, CX still provides type inference in some cases. For example, instead of writing i32.add(5, 5) you can just write 5 + 5. In this case, CX is going to see that you're using 32-bit integers, and the parser is going to transform that expression to i32.add(5, 5). However, if you try to do 5 + 5L, i.e. if you try to add a 32-bit integer to a 64-bit integer, CX will throw a compile-time error because you're mixing types.

The proper way to handle types in CX is to explicitly parse everything. This way one can be sure that you're always going to be handling the desired type. So, retaking the previous example, you'd need to parse one of them to match the other's type, either i32.i64(5) + 5L or 5 + i64.i32(5L).

Primitive Types

There are seven primitive types in CX: bool, str, byte, i32, i64, f32, and f64. Those represent Booleans (true or false), character strings, bytes, 32-bit integers, 64-bit integers, single precision and double precision floating-point numbers, respectively.

Global variables

Global variables are different from local variables regarding scope. Global variables are available to any function defined in a package, and to any package that is importing the package that contains that global declaration. An example of some global variables is shown below.

package main

var global1 i32
var global2 i64

func foo () {
    i32.print(global1)
    i64.print(global2)
}

func main () {
    global1 = 5
    global2 = 5L

    i32.print(global1)
    i64.print(global2)
}

In the example above we can see that both the main and foo functions are printing the values of the two global variables defined. They are going to print the same values, as they are referring to the same variables.

Local variables

In contrast to global variables, local variables are constrained to the function where they are declared. This means that is not possible for another function to call a variable defined in another function.

package main

func foo () {
	i32.print(local) // this expression will throw a compile-time error
}

func main () {
	var local i32
	local = 5

	i32.print(5)
	foo()
}

If you try to run the example above, CX will throw an error similar to this: error: examples/testing.cx:4 identifier 'local' does not exist, so CX will not even try to run that program. If we could de-activate CX's compile-time type checking, and the program above could make it to the runtime, CX would not print 5 when running foo(), as that function is unaware of that variable.

Arrays

Arrays (or vectors) and multi-dimensional arrays (or matrices) can be declared using a syntax similar to C's.

package main

type Point struct {
    x i32
    y i32
}

func main () {
    var arr1 [5]i32
    var arr2 [5]Point
    var arr3 [2][2]f32

    arr1[0] = 10
    arr2[1] = 20
}

In the example above we see the declaration of an array of 5 elements of type i32, followed by an array of the same cardinality but of type Point, which is a custom type. Custom types are discussed in a later section. Lastly, we see an example of a 2x2 matrix of type f32.

Lastly, we can see how we can initialize an array using the bracket notation, e.g. arr1[0] = 10.

Slices

Golang-like slices exist in CX (dynamic arrays). Slices are declared similarly to arrays, with the only difference that the size is omitted.

package main

type Point struct {
    x i32
    y i32
}

func main () {
    var slc1 []i32
    var slc2 []Point
    var slc3 [][]f32
}

Slices, unlike arrays, cannot be directly initialized using the bracket notation (unless you use the native function make first). You can use the bracket notation to reassign values to a slice, once an element associated to the index that you want to use already exists, as shown in the example below.

package main

func main () {
    var slc []i32

    slc = append(slc, 1)
    slc = append(slc, 2)

    slc[0] = 10
    slc[2] = 30 // This is not allowed, as len(slc) == 2, not 3
}

As this behavior is more related to the logic behind slices, it is further explained in the Runtime->Data Structures->Slices section.

Literals

A literal is any data structure that is not being referenced by any variable yet. For example: 1, true, []i32{1, 2, 3}, Point{x: 10, y: 20}.

Particularly, it is worth noting the cases of array, slice and struct literals.

package main

type Point struct {
    x i32
    y i32
}

func main () {
    var a Point
    var b [5]i32
    var c []i32

    a = Point{x: 10, y: 20}
    b = [5]i32{1, 2, 3, 4, 5}
    c = []i32{100, 200, 300}
}

In the example above we can see examples of struct (Point{x: 10, y: 20}), array ([5]i32{1, 2, 3, 4, 5}), and slice ([]i32{100, 200, 300}) literals, in that order. These literals exist to simplify the creation of such data structures.

Functions

Functions in CX are similar in syntax to functions in Go. The only exception is that named outputs are enforced at the moment (this will most likely change in the future).

package main

func foo () {

}

func main () {
	foo()
}

The example above doesn't do anything, but it illustrates the anatomy of a function. In the case of foo, we have an empty function declaration, and then we have main, which is defined by a single call to foo. Functions can also receive inputs and return outputs, as in the example below.

package main

func foo (in i32) {
    i32.print(in) // this will print 5
}

func bar () (out i32){
    out = 10
}

func main () {
    foo(5)

    var local i32
    local = bar()
    i32.print(local) // this will print 10
}

In this case, foo is declared to receive one input parameter, and bar is declared to return one output parameter.

Custom Types

If primitive types are not enough, you can define your own custom types by combining the primitive types and other constructs like slices, arrays, and even other custom types.

package main

type Point struct {
    x i32
    y i32
}

func main () {
    var p Point
    p.x = 10
    p.y = 20

    printf("Point coordinates: (%d, %d)\n", p.x, p.y)
}

In the example above, we can see a custom type that defines a Point as the combination of two 32-bit integers (i32). After declaring the custom type, you can start declaring variables of that type anywhere in the package where it was declared in. The code in foo shows how you can create and use an instance of that structure.

Methods

A variation of functions that are associated to custom types are methods.

package main

type Point struct {
	x i32
	y i32
}

type Line struct {
	a Point
	b Point
}

func (p Point) print () {
	printf("Point coordinates: (%d, %d)\n", p.x, p.y)
}

func (l Line) print () {
	printf("Line point A: (%d, %d), Line point B: (%d, %d)\n", l.a.x, l.a.y, l.b.x, l.b.y)
}

func main () {
	var l Line
	var p1 Point
	var p2 Point

	p1.x = 10
	p1.y = 20
	p2.x = 11
	p2.y = 21

	l.a = p1
	l.b = p2

	p1.print()
	p2.print()
	l.print()
}

In the example above, we define two custom types: Point and Line. The type line is defined by two fields of type Point, and the type Point is defined as coordinate defined by two fields of type i32.

As a simple example, we create two methods called print, one for the type Point and another for the type Line. In the case of Point.print, we just print the two coordinates, and in the case of Line.print we print the coordinates of the two points that define the Line instance.

Packages

In the previous examples we have always been using a single package: main. If your program grows too large it's convenient to divide your code into different packages.

package foo

func fn (in i32) {
    i32.print(in)
}

package bar

func fn () (out i32) {
    out = 5
}

package main
import "foo"
import "bar"

func main () {
    foo.fn(10) // prints 10

    var num i32
    num = bar.fn()

    i32.print(num) // prints
}

In the example above, we can see how two functions with the same name (fn) are declared, each in a separate package. Both of these functions have different signatures, as foo.fn accepts a single input parameter and bar.fn doesn't accept any inputs but returns a single output parameter.

We can then see how the main package imports both the foo and bar packages, to later call each of these functions.

Statements

Statements are different to declarations, as they don't create any named elements in a program. They are used to control the flow of a program.

If and if/else

The most basic statement is the if statement, which is going to execute a block of code only if a condition is true.

package main

func main () {
    if false {
        str.print("This will never print")
    }
}

The example above won't do anything, as the condition for the if statement is always going to evaluate to false.

package main

func main () {
    if true {
        str.print("This will always print")
    }
}

In contrast, the example above will always print.

package main

func main () {
    if true {
        str.print("This will always print")
    } else {
        str.print("This will never print")
    }
}

Lastly, the example above shows how to write an if/else statement in CX.

As a note about its syntax, the predicates or conditions don't need to be enclosed in parentheses, just like in Go.

Else if

Instead of simply adding one alternative path, you can string together a series of else if blocks, which check for as many different conditions as you like. Giving you similar functionality as Go's switch/select blocks (containing various conditions/cases).

package main

func main () {
   var i i32
   i = 0

   if i == 0 {
     str.print("i is 0")
   } else if i == 1 {
     str.print("i is 1")
   } else if i == 2 {
     str.print("i is 2")
   } else {
     str.print("i is NOT 0, 1 or 2")
   }
}

For loop

CX's only looping statement is the for loop. Similar to Go, the for loop in CX can be used as the while statement in other programming languages, and as a traditional for statement.

package main

func main () {
	for true {
		str.print("forever")
	}
}

As the simplest example of a loop, we have the infinite loop shown in the example above. In this case, the loop will print the character string "forever" indefinitely. If you try this code, remember that you can cancel the program's execution by hitting Ctrl-C.

package main

func main () {
	for str.eq("hi", "hi") {
		str.print("hi")
	}
}

The code above shows another example, one where we use an expression as its predicate, rather than a literal true or false. It is worth mentioning that you can replace str.eq("hi", "hi") by "hi" == "hi".

package main

func main () {
	var c i32
	for c = 0 ; c < 10; c++ {
		i32.print(c)
	}
}

The traditional for loop shown in the example above. In languages like C, you need to first declare your counter variable, and then you have the option to initialize or reassign the counter in the first part of the for loop. The second part of the for loop is reserved for the predicate, and the last part is usually used to increment the counter. Nevertheless, just like in C, there's nothing stopping you from doing whatever you want in the first and last parts. However, the predicate part needs to be an expression that evaluates to a Boolean.

package main

func main () {
	for c := 0; c < 10; c++ {
		i32.print(c)
	}
}

A more Go-ish way of declaring and initializing the counter is to use an inline declaration, as seen in the example above.

package main

func main () {
	var c i32
	c = 0
	for ; c < 10; c++ {
		i32.print(c)
	}
}

Lastly, the for loop can also completely omit the initialization part, as seen above.

Goto

goto can be used to immediately jump the execution of a program to the corresponding labeled expression.

package main

func main () (out i32) {
	goto label2
label1:
	str.print("this should never be reached")
label2:
	str.print("this should be printed")
}

In the example above, we see how a goto statement forces CX to ignore executing the expression labeled as label1, and instead jumps to the label2 expression.

Expressions

Expressions are basically function calls. But the term expression also takes into consideration the variables that are receiving the function's output arguments, the input arguments, and any dereference operations.

package main

func foo () (arr [2]i32) {
    arr = [2]i32{10, 20}
}

func main () {
    i32.print(foo()[0])
}

For example, the expression i32.print(foo()[0]) in the code above consists of two function calls, and the array returned by the call to foo is "dereferenced" to its 0th element.

Assignments and Initializations

As in many other C-like languages, assignments are done using the equal (=) sign.

package main

func main () {
    var foo i32
    foo = 5
    foo = 50
}

In the case of the code above, the variable foo is declared and then initialized to 5 using the = sign. Then we reassign the foo variable to the value 50.

package main

func main () {
    foo := 5
    foo = 50
}

As in other programming languages, short variable declarations exist in CX. The := token can be used to tell CX to infer a variable's type. This way, CX declares and initializes at the same time, as seen in the example above.

Affordances

The affordance system in CX uses a special operator: ->. This operator takes a series of statements that have the form of function calls, and transforms them to a series of instructions that can be internally interpreted by the affordance system.

package main

func exprPredicate (expr Expression) (res bool) {
	if expr.Operator == "i32.add" {
		res = true
	}
}

func prgrmPredicate (prgrm Program) () {
	if prgrm.FreeHeap > 50 {
		res = true
	}
}

func main () {
	num1 := 5
	num2 := 10

targetExpr:
	sum := i32.add(0, 0)

	tgt := ->{
		pkg(main)
		fn(main)
		expr(targetExpr)
	}

	fltrs := ->{
		filter(exprPredicate)
		filter(prgrmPredicate)
	}

	aff.print(tgt)
	aff.print(fltrs)

	affs := aff.query(fltrs, tgt)

	aff.on(affs, tgt)
	aff.of(affs, tgt)

	aff.inform(affs, 0, tgt)
	aff.request(affs, 0, tgt)
}

Runtime

The previous section presents the language features from a syntax perspective. In this section we'll cover what's the logic behind these features: how they interact with other elements in your program, and what are the intrinsic capabilities of each of these features.

Packages

Packages are CX's mechanism for better organizing your code. Although it is theoretically possible to store a big project in a single package, the code will most likely become very hard to understand. In CX the programmer is encouraged to place the files that define the code of a package in separate directory. Any subdirectory in a package's directory should also contain only source code files that define elements of the same package. Nevertheless, CX will not throw any error if you don't follow this way of laying out your source files. In fact, you can declare different packages in a single source code file.

Data Structures

Data structures are particular arrangements of bytes that the language interprets and stores in special ways. The most basic data structures represent basic data, such as numbers and character strings, but these basic types can be used to construct more complex data types.

Literals

A literal is any data structure that is not being referenced by any variable yet. For example: 1, true, []i32{1, 2, 3}, Point{x: 10, y: 20}.

It's important to make a distinction, particularly with arrays, slices and struct instances.

package main

type Point struct {
	x i32
	y i32
}

func main () {
	var p1 Point
	p1.x = 10
	p1.y = 20

	p2 := Point{x: 11, y: 21}

	i32.print(p2.x)
	i32.print(p2.y)
}

In the example above we are creating two instances of the Point type. The first method we use does not involve struct literals, as a variable of that type is first created and then initialized.

In the second case (p2), the full struct instance is first created. CX creates an anonymous struct instance as soon as it encounters Points{x: 11, y: 21}, and then it proceeds to assign that literal to the p2 variable, using short variable declarations.

package main

func main () {
	var arr1 [3]i32
	arr1[0] = 1
	arr1[1] = 2
	arr1[2] = 3

	arr2 := [3]i32{10, 20, 30}
}
package main

func main () {
	var slc1 []i32
	slc1 = append(slc1, 1)
	slc1 = append(slc1, 2)
	slc1 = append(slc1, 3)

	slc2 := []i32{10, 20, 30}
}

Similarly, in the two examples above we can see how we can declare array and slice variables and then we initialize them. In the case of arrays, we use the bracket notation, and for slices we have to use append, as slc1 starts with a size and capacity of 0. In the cases of arr2 and slc2, we use literals to initialize them more conveniently.

Regarding numbers, you need to be aware that implicit casting does not exist in CX. This means that the number 34 cannot be assigned to a variable of type i64. In order to assign it, you need to either parse it using the native function i32.i64 or you can create a 64-bit integer literal. To create a number literal of a type other than i32, you can use different suffixes: B, L and D, for byte, i64 (long) and f64, respectively. So, assuming foo is of type i64, you can do this assignment: foo = 34L.

Variables

When CX compiles a program, it knows how many bytes need to be reserved in the stack for each of the functions. CX can know this thanks to variable declarations.

package main

type Point struct {
    x i32
    y i32
}

func foo (inp Point) {
    var test1 i64
    var test2 bool
}

func main () {
    var test3 i32
    var test4 f32
}

The two functions declared in the example above are going to reserve 17 and 8 bytes in the stack, respectively. In the case of the first function, foo needs to reserve space for an input parameter of type Point, which requires 8 bytes (because of the two i32 fields), and two local variables: one 64-bit integer that requires 8 bytes and a Boolean that requires a single byte. In the case of main, CX needs to reserve bytes for two local variables: a 32-bit integer and a single-precision floating point number, where each of them require 4 bytes.

package main

var global1 i32

func main () {
    var local i32
}

Local variables are different than global variables. In order for globals to have a global scope they need to be allocated in a different memory segment than local variables. This different memory segment does not shrink or get bigger like the stack. This means that any global variable is going to be kept "alive" as long as the program keeps being executed.

A global scope means that variables of this type are accessible to any function declared in the same package where the variable is declared, and to any function of other packages that are importing this package.

package main

func main () {
    var foo i32
    i32.print(foo) // prints 0
}

In CX every variable is going to initially point to a nil value. This nil value is basically a series of one or more zeroes, depending on the size of the data type of a given variable. For example, in the code above we see that we have declared a variable of type i32 and we immediately print its value without initializing it. This CX program will print 0, as the value of foo is [0 0 0 0] in the stack (4 zeroes, as a 32-bit integer is represented by 4 bytes).

In the case of data types that point to variable-sized structures, such as slices or character strings, these are initialized to a nil pointer, which is represented by 4 zeroed bytes. This nil pointer is located in the heap memory segment, instead of the stack.

Primitive types

There are seven primitive types in CX: bool, str, byte, i32, i64, f32, and f64. These types can be used to construct other more complex types, as will be seen in the next sections.

bool and byte both require a single byte to represent their values. In the case of bool, there are only two possible values: true or false. In the case of byte you can represent up to 256 values, which range from 0 to 255. Next in size, we have i32 and f32 , where both of them require 4 bytes, and then we have i64 and f64, which require 8 bytes each.

Now, strings are special as they are static and dynamic sized at the same time. If you have a look at how a variable of type str reserves memory in the stack, you'll see that it requires 4 bytes, regardless of what text it's pointing to. The explanation behind this is that any str in CX actually behaves like a pointer behind the scenes, and the actual string gets stored in the heap memory segment.

package main

func main () {
	var foo str

	foo = str.concat("Hello, ", "World!")
	foo = "Hi"
}

When CX compiles the example above, three strings are first stored in the data memory segment (just like global variables, as these strings are constants, memory-wise): "Hello, ", "World" and "Hi". When the program is executed, str.concat is called, which creates a new string by concatenating "Hello, " and "World!", and this new character string is allocated in the heap memory segment. Then foo is assigned only the address of this new character string. Then we immediately re-assign foo with the address of "Hi". This means that foo was first assigned a memory address located in the data memory segment, and then it was assigned an address located in the heap.

Arrays

Arrays, as in other programming languages, are used to create collections of data structures. These data structures can be primitive types, custom types or even arrays or slices.

package main

type Point struct {
    x i32
    y i32
}

func main () {
    var [5]i32
    var [5]Point
}

In the example above, we're creating two arrays, one of a primitive type and the other one of a custom type. CX reserves memory for these arrays in the stack as soon as the function that contains them is called. In this case, 60 bytes are going to be reserved for main as soon as the program starts its execution, as main acts as the program's entry point. You need to be careful with arrays, as those can easily fill up your memory, especially with multi-dimensional arrays (or matrices).

Also, another point to consider is performance. While accessing arrays is almost as fast as accessing an atomic variable, arrays can be troublesome when being sent/received as to/from functions. The reason behind this is that an array needs to be copied whenever it is sent to another function. If you're working with arrays of millions of elements and you need to be sending that arrays millions of times to another function, it's going to impact your program's performance a lot. A way to avoid this is to either use pointers to arrays or slices.

Slices

Dynamic arrays don't exist in CX. This means that the following code is not a valid CX program:

package main

func main () {
    var size i32
    size = 13
    var arr [size] // this is not valid
}

If you need an array that can grow in size as required, you need to use slices. Behind the scenes, slices are just arrays with some extra features. First of all, any slice in CX goes directly to the heap, as it's a data structure that is going to be changing in size. In contrast, arrays are always going to be stored in the stack, unless we're handling pointers to arrays. However, this behavior may change in the future, when CX's escape analysis mechanism improves (for example, the compiler can determine if an array is never going to change its size, and decide to keep it in the stack).

The second characteristic of slices in CX is how they change their size. Any slice, when it's first declared, starts with a size and capacity of 0. The size represents how many elements are in a given slice, while the capacity represents how many elements can be allocated in that slice without having to be relocated in the heap.

package main

func main () {
	var slc []i32

	slc = append(slc, 1)
	slc = append(slc, 2)
	slc = append(slc, 3)
	slc = append(slc, 4)
}

In the code above we can see how we declare a slice and then we initialize it using the appendfunction. After all the appends, we'll end up with a slice of size 4 and capacity 4, and this appending process will create the following objects in the heap:

[0 0 0 0 0 12 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 16 0 0 0 2 0 0 0 2 0 0 0 1 0 0 0 2 0 0 0 0 0 0 0 0 24 0 0 0 4 0 0 0 4 0 0 0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0]

First, the slice slc starts with 0 objects in it; it is pointing to nil. Then, after the first append, the object [0 0 0 0 0 12 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0] is allocated to the heap. The first five bytes are used by CX's garbage collector. The next 4 bytes indicate the size of the object, and the remaining bytes are the actual slice slc. The first four bytes of slc tell us its current size, while the next four tell us its capacity. The remaining bytes of this object are the elements of the slice.

The following object, [0 0 0 0 0 16 0 0 0 2 0 0 0 2 0 0 0 1 0 0 0 2 0 0 0], shows now a size of 2 and a capacity of 2, with the 32-bit integers 1 and 2 as its elements. The last object, 0 0 0 0 0 24 0 0 0 4 0 0 0 4 0 0 0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0, needs careful attention. We can see that our objects jumped from size 1 to 2 and finally 4. The same happened to its capacity, and the containing elements are now 1, 2, 3 and 4. What happened to the slice of size 3 and capacity 3? First of all, capacities are increased by getting doubled each time the size of an object is greater than its capacity, so we would never get a slice of capacity 4 by following this method. Next, we need to think on what is capacity used for.

Slices are just arrays, which means that they can't be resized. The dynamic nature of slices is emulated by copying the full slice to somewhere else in memory, but with a greater capacity. However, this will only happen if adding a new element to the existing slice would overflow it. This is why slices keep track of two metrics: size and capacity, i.e. how many actual elements are in the slice, and how many elements the currently allocated slice can hold, respectively.

package main

func main () {
    var arr1 [1]i32
    arr1[0] = 1 // add the first value

    var arr2 [2]i32 // double the size
    arr2[0] = arr1[0] // copy previous array
    arr2[1] = 2 // add the second value

    var arr3 [4]i32 // double the size
    arr3[0] = arr2[0] // copy previous array
    arr3[1] = arr2[1] // copy previous array

    arr3[2] = 3 // add the third value
    arr3[3] = 4 // add the fourth value
}

The example above shows the behavior of the slice in the previous example, but using arrays.

Structures

Structures are CX's mechanism for creating custom types, as in many other C-like languages. Structures are basically a grouping of other primitive or custom types (called fields) that together create another type of data structure. For example, a point can be defined by its coordinates in a two-dimensional space. In order to create a type Point, you can use a structure that contains two fields of type i32, one for x and another for y, as in the example below.

package main

type Point struct {
	x i32
	y i32
}

func main () {
	var p Point
	p.x = 10
	p.y = 20
}

Whenever an instance of a structure is created by either declaring a variable of that type or by creating a literal of that type, CX reserves memory to hold space for all the fields defined in the structure declaration. Like in C, the bytes are reserved depending on the order of the fields in the structure declaration.

package main

type struct1 struct {
	field1 bool
	field2 i32
	field3 i64
}

type struct2 struct {
	field1 i64
	field2 bool
	field3 i32
}

func main () {
	var s1 struct1
	var s2 struct2
}

For example, in the code above a call to main will reserve a total of 26 bytes in the stack. In the case of the first struct instance, the first byte is going to represent field1 of type bool, the next four bytes are going to represent field2 of type i32, and the final 8 bytes are going to represent field3 of type i64. In the case of the next struct instance, the first eight bytes represent an i64 field so, although both struct instances contain the same number of fields and of the same type, the byte layout changes.

Pointers

Sometimes it's useful to pass variables to functions by reference instead of by value.

package main
import "time"

func foo (nums [100][100]i32) {
	// do something with nums
}

func main () {
	var start i64
	var end i64
	var nums [100][100]i32

	start = time.UnixMilli()

	for c := 0; c < 10000; c++ {
		foo(nums)
	}

	end = time.UnixMilli()

	printf("elapsed time: \t%d milliseconds\n", end - start)
}

The example above is very inefficient, as CX is going to be sending a 10,000 element matrix to foo 10,000 times. Every time foo is called, every byte of that matrix needs to be copied for foo. In my computer the example above takes around 638 milliseconds to run.

package main
import "time"

func foo (nums *[100][100]i32) {
	// do something with nums
}

func main () {
	var start i64
	var end i64
	var nums [100][100]i32

	start = time.UnixMilli()

	for c := 0; c < 10000; c++ {
		foo(&nums)
	}

	end = time.UnixMilli()

	printf("elapsed time: \t%d milliseconds\n", end - start)
}

A new version of the last program is shown above. In contrast to the last program, the code above sends a pointer to the matrix to foo. A pointer in CX uses only 4 bytes (in the future, pointers will use 8 bytes in 64-bit systems and 4 bytes in 32-bit systems), so instead of copying 10,000 bytes, we only copy 4 bytes to foo every time we call it. This version of the program takes only 3 milliseconds to run in my computer.

package main

func foo (inp i32) {
	inp = 10
}

func main () {
	var num i32
	num = 15
	i32.print(num) // prints 15
	foo(num)
	i32.print(num) // prints 15
}

In the example above, we sendnum to foo, and then we re-assign the input's value to 10. If we print the value of num before and after calling foo, we can see that in both instances 15 will be printed to the console.

package main

func foo (num *i32) {
	*num = 10
}

func main () {
	var num i32
	num = 15
	i32.print(num) // prints 15
	foo(&num)
	i32.print(num) // prints 10
}

The code above is a pointer-version of the previous example. In this case, instead of sending num by value, we send it by reference, using the & operator. foo also changed, and it now accepts a pointer to a 32-bit integer, i.e. *i32. After running the example, you'll notice that, this time, foo is now changing num's value.

Escape Analysis

Consider the following example:

package main

func foo () (pNum *i32) {
	var num i32
	num = 5 // this is in the stack

	pNum = &num
}

func stackDestroyer () {
	var arr [5]i32
}

func main () {
	var pNum *i32
	pNum = foo()

	stackDestroyer()

	i32.print(*pNum)
}

If we store foo's num's value (5) in the stack, and then we call stackDestroyer, isn't arr going to overwrite the bytes storing the 5? This doesn't happen, because that 5 is now in the heap. But this doesn't mean that any value being pointed to is going to be moved to the heap. For example, let's re-examine one of the examples presented in the Pointers section:

package main

func foo (num *i32) {
	*num = 10
}

func main () {
	var num i32
	num = 15
	i32.print(num) // prints 15
	foo(&num)
	i32.print(num) // prints 10
}

If any value being pointed to by a pointer was sent to the heap, we wouldn't be able to change nums value, which is stored in the stack; we would be changing the heap's copied value.

package main

func foo () (pNum *i32) {
	var num i32
	var pNum *i32

	num = 5

	pNum = &num
}

func main () {
	var pNum *i32
	pNum = foo()

	i32.print(*pNum) // prints 5, which is stored in the heap
}

Basically, in order to fix this problem, whenever a pointer needs to be returned from a function, the value it is pointing to "escapes" to the heap. In the example above, we can see that num's value is going to be preserved by escaping to the heap, as we are returning a pointer to it from foo.

package main

func foo () (pNum *i32) {
	var num i32
	var pNum *i32

	num = 5 // this is in the stack

	pNum = &num // the pointer will be returned, so the value is sent to the heap
}

func stackDestroyer () {
	var arr [5]i32
}

func main () {
	var pNum *i32
	pNum = foo()
	stackDestroyer() // if 5 does not escape, it would be destroyed by this function

	i32.print(*pNum) // prints 5, which is stored in the heap
}

We can check this behavior even further in the example above. After calling foo, we call stackDestroyer, which overwrites the following 20 bytes after main's stack frame. Yet, when we call i32.print(*pNum), we'll see that we still have access to a 5. This 5 is not the one created in foo, though, but a copy of it that was allocated in the heap.

Control Flow

Once we have the appropriate data structures for our program, we'll now need to process them. In order to do so, we need to have access to some control flow structures.

Functions

Functions are used to encapsulate routines that we plan to be frequently calling. In addition to encapsulating a series of expressions and statements, we can also receive input parameters and return output parameters, just like mathematical functions.

package main

func main () {
	var players []str
	players = []str{"Richard", "Mario", "Edward"}

	str.print("=======================")
	str.print(str.concat("Name: \t", players[0]))
	str.print("=======================")

	str.print("=======================")
	str.print(str.concat("Name: \t", players[1]))
	str.print("=======================")

	str.print("=======================")
	str.print(str.concat("Name: \t", players[2]))
	str.print("=======================")
}

For example, if we see the code above we'll notice that it seems repetitive. We can fix this by creating a function, as seen in the example below.

package main

func drawBox (player str) {
	str.print("=======================")
	str.print(str.concat("Name: \t", player))
	str.print("=======================")
}

func main () {
	var players []str
	players = []str{"Richard", "Mario", "Edward"}

	drawBox(players[0])
	drawBox(players[1])
	drawBox(players[2])
}

Methods

Methods are useful when we want to associate a particular function to a particular custom type (associating functions to primitive types is not allowed). This allows us to create more readable code.

package main

type Player struct {
	Name str
	HP i32
	Mana i32
	Lives i32
}

type Monster struct {
	Name str
	HP i32
	Mana i32
}

func (player Player) draw () {
	str.print(sprintf("\n\tName: \t%s\n\tHP: \t%d\n\tMana: \t%d\n\tLives: \t%d\n\n%s",
		player.Name,
		player.HP,
		player.Mana,
		player.Lives,
		`
─▄████▄▄░
▄▀█▀▐└─┐░░
█▄▐▌▄█▄┘██
└▄▄▄▄▄┘███
██▒█▒███▀`))
}

func (monster Monster) draw () {
	str.print(sprintf("\n\tName: \t%s\n\tHP: \t%d\n\tMana: \t%d\n\n%s",
		monster.Name,
		monster.HP,
		monster.Mana,
		`
╲╲╭━━━━╮╲╲
╭╮┃▆┈┈▆┃╭╮
┃╰┫▽▽▽▽┣╯┃
╰━┫△△△△┣━╯
╲╲┃┈┈┈┈┃╲╲
╲╲┃┈┏┓┈┃╲╲
▔▔╰━╯╰━╯▔▔`))
}

func main () {
	var player Player
	player.Name = "Mario"
	player.HP = 10
	player.Mana = 10
	player.Lives = 3

	player.draw()

	var monster Monster
	monster.Name = "Domo-kun"
	monster.HP = 7
	monster.Mana = 4

	monster.draw()
}

The example above shows us how we can create two versions of the function draw, and the behavior of each depends on the custom type that we're using to call it.

If and if/else

if and if/else statements are used to execute a block of instructions only if certain condition is true or false. Behind the scenes, if and if/else statements are parsed to a series of jmp instructions internally. For example, in the case of an if statement, we will jump 0 instructions if certain predicate is true, and it will jump n instructions if the predicate is false, where n is the number of instructions in the if block of instructions.

package main

func main () {
	if true {
		str.print("hi")
	}
	str.print("bye")
}
Program
0.- Package: main
	Functions
		0.- Function: main () ()
			0.- Expression: jmp(true bool)
			1.- Expression: str.print("" str)
			2.- Expression: jmp(true bool)
			3.- Expression: str.print("" str)
		1.- Function: *init () ()

In the two code snippets above we can see how an if statement is translated by the parser to a set of two jmp instructions. These jmp instructions have some meta data in them that is not shown in the second snippet: how many lines to jump if its predicate is true and how many lines to jump if the predicate is false. jmp is not meant to be used by CX programmers (it's only part of the CX base language), so you don't need to worry about it.

package main

type Player struct {
	Name str
	HP i32
	Mana i32
	Lives i32
}

type Monster struct {
	Name str
	HP i32
	Mana i32
}

func main () {
	var player Player
	player.Name = "Mario"
	player.HP = 10
	player.Mana = 10
	player.Lives = 3

	var monster Monster
	monster.Name = "Domo-kun"
	monster.HP = 7
	monster.Mana = 4

	if player.HP < 5 {
		str.print("===DANGER!===")
	} else {
		str.print("===YOU CAN DO IT!===")
	}

	if monster.HP < 10 {
		str.print(sprintf("===%s is bleeding!===", monster.Name))
	}

	if monster.HP < 5 {
		str.print(sprintf("===%s is dying!===", monster.Name))
	}

	if monster.HP == 0 {
		str.print(sprintf("===%s is dead!===", monster.Name))
	}
}

Continuing with the example from the previous section (to some extent), let's use if and if/else statements to determine what messages are going to be displayed to the user. These messages represent the state of the player or the monster, depending on their hit points (HP).

For loop

The for loop is the only looping mechanism in CX. Just like if and if/else statements are constructed using jmp statements, for loop statements are also constructed the same way.

package main

func main () {
	for c := 0; c < 10; c++ {
		i32.print(c)
	}
}
Program
0.- Package: main
	Functions
		0.- Function: main () ()
			0.- Declaration: c i32
			1.- Expression: c i32 = identity(0 i32)
			2.- Expression: *lcl_0 bool = lt(c i32, 10 i32)
			3.- Expression: jmp(*lcl_0 bool)
			4.- Expression: i32.print(c i32)
			5.- Declaration: c i32
			6.- Expression: c i32 = i32.add(c i32, 1 i32)
			7.- Expression: jmp(true bool)
		1.- Function: *init () ()

The code snippets above illustrate how a for loop that counts from 0 to 9 is translated to a set of of jmp instructions.

package main

type Player struct {
	Name str
	HP i32
	Mana i32
	Lives i32
}

type Monster struct {
	Name str
	HP i32
	Mana i32
}

func (player Player) draw () {
	str.print(sprintf("\n\tName: \t%s\n\tHP: \t%d\n\tMana: \t%d\n\tLives: \t%d\n\n%s",
		player.Name,
		player.HP,
		player.Mana,
		player.Lives,
		`
─▄████▄▄░
▄▀█▀▐└─┐░░
█▄▐▌▄█▄┘██
└▄▄▄▄▄┘███
██▒█▒███▀`))
}

func (monster Monster) draw () {
	str.print(sprintf("\n\tName: \t%s\n\tHP: \t%d\n\tMana: \t%d\n\n%s",
		monster.Name,
		monster.HP,
		monster.Mana,
		`
╲╲╭━━━━╮╲╲
╭╮┃▆┈┈▆┃╭╮
┃╰┫▽▽▽▽┣╯┃
╰━┫△△△△┣━╯
╲╲┃┈┈┈┈┃╲╲
╲╲┃┈┏┓┈┃╲╲
▔▔╰━╯╰━╯▔▔`))
}

func (player Player) attack (cmd str, monster *Monster) {
	if bool.or(cmd == "M", cmd == "m") {
		var dmg i32
		dmg = i32.rand(1, 4)
		(*monster).HP = (*monster).HP - dmg
		printf("'%s' suffered a magic attack. Lost %d HP. New HP is %d\n", (*monster).Name, dmg, (*monster).HP)
	} else {
		var dmg i32
		dmg = i32.rand(1, 2)
		(*monster).HP = (*monster).HP - dmg
		printf("'%s' suffered a physical attack. Lost %d HP. New HP is %d\n", (*monster).Name, dmg, (*monster).HP)
	}
}

func (monster Monster) attack (cmd str, player *Player) {
	var dmg i32
	dmg = i32.rand(1, 5)
	(*player).HP = (*player).HP - dmg

	printf("'%s' suffered a physical attack. Lost %d HP. New HP is %d\n", (*player).Name, dmg, (*player).HP)
}

func battleStatus (player Player, monster Monster) {
	if player.HP < 5 {
		str.print("===DANGER!===")
	} else {
		str.print("===YOU CAN DO IT!===")
	}

	if player.HP == 0 {
		str.print("===YOU DIED===")
	}

	if monster.HP < 10 && monster.HP >= 5 {
		str.print(sprintf("===%s is bleeding!===", monster.Name))
	}

	if monster.HP < 5 && monster.HP > 0 {
		str.print(sprintf("===%s is dying!===", monster.Name))
	}

	if monster.HP <= 0 {
		str.print(sprintf("===%s is dead!===", monster.Name))
	}
}

func main () {
	var player Player
	player.Name = "Mario"
	player.HP = 10
	player.Mana = 10
	player.Lives = 3

	var monster Monster
	monster.Name = "Domo-kun"
	monster.HP = 7
	monster.Mana = 4

	player.draw()
	monster.draw()

	for true {
		if player.HP < 1 || monster.HP < 1 {
			return
		}

		printf("Command? (M)agic; (P)hysical; (E)xit\t")
		var cmd str
		cmd = read()

		if cmd == "E" || cmd == "e" {
			return
		}

		player.draw()
		monster.draw()

		player.attack(cmd, &monster)
		monster.attack(cmd, &player)
		battleStatus(player, monster)
	}
}

Lastly, we can see how we use a for loop to create something similar to a REPL for the program that we have been building in the last few sections.

Go-to

The last control flow mechanism is go-to, which is achieved through the goto statement.

package main

func main () (out i32) {
beginning:
	printf("What animal do you like the most: (C)at; (D)og; (P)igeon\n")

	var cmd str
	cmd = read()

	if cmd == "C" || cmd == "c" {
		goto cat
	}

	if cmd == "D" || cmd == "d" {
		goto dog
	}

	if cmd == "P" || cmd == "p" {
		goto pigeon
	}

cat:
	str.print("meow")
	goto beginning
dog:
	str.print("woof")
	goto beginning
pigeon:
	str.print("tweet")
	goto beginning
}

The program above creates an infinite loop by using gotos. The loop will keep asking the user to input commands, and will jump to certain expression depending on the command.

Affordances

CX Affordances

Native Functions

Type-inferenced Functions

CX has a small set of functions that are not associated to a single type signature. For example, instead of using i32.add to add two 32-bit integers, you can use the generalized add function. Furthermore, whenever you use arithmetic operators, such as +, - or %, these are translated to their corresponding "type-inferenced" function, e.g. num = 5 + 5 is translated to num = i32.add(5, 5). These native functions still follow CX's philosophy of having a strict typing system, as the types of the arguments sent to these native functions must be the same.

Note that after listing a group of similar "type-inferenced" functions below, we list the compatible types for the corresponding functions.

eq

uneq

Note: the preceding functions only work with arguments of type bool, byte, str, i32, i64, f32 or f64.

Example

package main

func main () {
	bool.print(eq(5, 5))
	bool.print(5 == 5) // alternative

	bool.print(uneq("hihi", "byebye"))
	bool.print("hihi" != "byebye") // alternative
}

lt

gt

lteq

gteq

Note: the preceding function only works with arguments of type byte, bool, str, i32, i64, f32 or f64.

Example

package main

func main () {
	bool.print(lt(3B, 4B))
	bool.print(3B < 4B) // alternative

	bool.print(gt("hello", "hi!"))
	bool.print("hello" > "hi!") // alternative

	bool.print(lteq(5.3D, 5.3D))
	bool.print(5.3D <= 5.3D) // alternative

	bool.print(gteq(10L, 3L))
	bool.print(10L >= 3L) // alternative
}

bitand

bitor

bitxor

bitclear

bitshl

bitshr

Note: the preceding functions only work with arguments of type i32 or i64.

Example

package main

func main () {
	i32.print(bitand(5, 1))
	i32.print(5 & 1) // alternative

	i64.print(bitor(3L, 2L))
	i64.print(3L | 2L) // alternative

	i32.print(bitxor(10, 2))
	i32.print(10 ^ 2) // alternative

	i64.print(bitclear(5L, 2L))
	i64.print(5L &^ 2L) // alternative

	i32.print(bitshl(2, 3))
	i32.print(2 << 3) // alternative

	i32.print(bitshr(16, 3))
	i32.print(16 >> 3) // alternative
}

add

sub

mul

div

Note: the preceding functions only work with arguments of type byte, i32, i64, f32 or f64.

Example

package main

func main () {
	byte.print(add(5B, 10B))
	byte.print(5B + 10B) // alternative

	i32.print(sub(3, 7))
	i32.print(3 - 7) // alternative

	i64.print(mul(4L, 5L))
	i64.print(4L * 5L) // alternative

	f32.print(div(4.3, 2.1))
	f32.print(4.3 / 2.1) // alternative
}

mod

Note: the preceding function only works with arguments of type byte, i32 or i64.

Example

package main

func main () {
	byte.print(mod(5B, 3B))
	byte.print(5B % 3B) // alternative
}

len

Note: the preceding function only works with arguments of type str, arrays or slices.

Example

package main

func main () {
	var string str
	var array [5]i32
	var slice []i32

	string = "this should print 20"
	array = [5]i32{1, 2, 3, 4, 5}
	slice = []i32{10, 20, 30}

	i32.print(len(string)) // prints 20
	i32.print(len(array)) // prints 5
	i32.print(len(slice)) // prints 3
}

printf

Note: the preceding function requires a format str as its first argument, followed by any number of arguments of type str, i32, i64, f32 or f64. The format string recognizes the following directives: %s for strings, %d for integers and %f for floating point numbers.

Example

package main

func main () {
	var name str
	var age i32
	var wrongPI f32
	var error f64

	name = "Richard"
	age = 14
	wrongPI = 3.16
	error = 0.0000000000000001D

	printf("Hello, %s. My name is %s. I see that you calculated the value of PI wrong (%f). I think this is not so bad, considering your young age of %d. When I was %d years old, I remember I miscalculated it, too (I got %f as a result, using a numerical method). If you are using a numerical method, please consider reaching an error lower than %f to get an acceptable result, and not a ridiculous value such as %f. \n\nBest regards!\n", name, "Edward", wrongPI, age, 25, 3.1417, error, 0.1)
}

sprintf

Note: the preceding function requires a format str as its first argument, followed by any number of arguments of type str, i32, i64, f32 or f64. The format string recognizes the following directives: %s for strings, %d for integers and %f for floating point numbers.

package main

func main () {
	var reply str
	var name str
	var title str

	name = "Edward"
	title = "Richard 8 PI"

	reply = sprintf("Thank you for contacting our technical support, %s. We see that you are having trouble with our video game titled '%s', targetted to kids under age %d. If you provide us with your parents e-mail address, we'll be glad to help you!", name, title, 14)

	str.print(reply)
}

Slice Functions

append

Example

package main

func main () {
	var slc1 []i32
	slc1 = append(slc1, 1)
	slc1 = append(slc1, 2)

	var slc2 []i32
	slc2 = append(slc1, 3)
	slc2 = append(slc2, 4)

	i32.print(len(slc1)) // prints 2
	i32.print(len(slc2)) // prints 4
}

Input/Output Functions

The following functions are used to handle input from the user and to print output to a terminal.

read

Example

package main

func main () {
	var password str

	for true {
		printf("What's the password, kid? ")
		password = read()

		if password == "123" {
			str.print("Welcome back.")
			return
		} else {
			str.print("Wrong, but you'll get another chance.")
		}
	}
}

byte.print

bool.print

str.print

i32.print

i64.print

f32.print

f64.print

printf

Example

package main

func main () {
    byte.print(5B)
    bool.print(true)
    str.print("Hello!")
    i32.print(5)
    i64.print(5L)
    f32.print(5.0)
    f64.print(5.0D)
    printf("For a better example, check section Type-inferenced Functions'")
}

Parse Functions

All parse functions follow the same pattern: XXX.YYY where XXX is the receiving type and YYY is the target type. You can read these functions as "parse XXX to YYY".

byte.str

byte.i32

byte.i64

byte.f32

byte.f64

Example

package main

func main () {
	var b byte
	b = 30B

	str.print(str.concat("Hello, ", byte.str(b)))
	i32.print(5 + byte.i32(b))
	i64.print(10L + byte.i64(b))
	f32.print(33.3 + byte.f32(b))
	f64.print(50.111D + byte.f64(b))
}

i32.byte

i32.str

i32.i64

i32.f32

i32.f64

Example

package main

func main () {
	var num i32
	num = 43

	str.print(str.concat("Hello, ", i32.str(num)))
	byte.print(5B + i32.byte(num))
	i64.print(10L + i32.i64(num))
	f32.print(33.3 + i32.f32(num))
	f64.print(50.111D + i32.f64(num))
}

i64.byte

i64.str

i64.i32

i64.f32

i64.f64

Example

package main

func main () {
	var num i64
	num = 43L

	str.print(str.concat("Hello, ", i64.str(num)))
	byte.print(5B + i64.byte(num))
	i64.print(10L + i64.i64(num))
	f32.print(33.3 + i64.f32(num))
	f64.print(50.111D + i64.f64(num))
}

f32.byte

f32.str

f32.i32

f32.i64

f32.f64

Example

package main

func main () {
	var num f32
	num = 43.33

	str.print(str.concat("Hello, ", f32.str(num)))
	byte.print(5B + f32.byte(num))
	i32.print(33 + f32.f32(num))
	i64.print(10L + f32.i64(num))
	f64.print(50.111D + f32.f64(num))
}

f64.byte

f64.str

f64.i32

f64.i64

f64.f32

Example

package main

func main () {
	var num f64
	num = 43.33D

	str.print(str.concat("Hello, ", f64.str(num)))
	byte.print(5B + f64.byte(num))
	i32.print(33 + f64.f32(num))
	i64.print(10L + f64.i64(num))
	f32.print(50.111 + f64.f32(num))
}

str.byte

str.i32

str.i64

str.f32

str.f64

Example

package main

func main () {
	var num str
	num = "33"

	byte.print(5B + str.byte(num))
	i32.print(33 + str.f32(num))
	i64.print(10L + str.i64(num))
	f32.print(50.111 + str.f32(num))
	f64.print(50.111D + str.f32(num))
}

Unit Testing

The assert function is used to test the value of an expression against another value. This function is useful to test that a package is working as intended.

assert

Example

package main

func foo() (res str) {
    res = "Working well"
}

func main () {
    var results []bool

    results = append(results, assert(5 + 5, 10, "Something went wrong with 5 + 5"))
    results = append(results, assert(foo(), "Working well", "Something went wrong with foo()"))

    var successfulTests i32
	for c := 0; c < len(results); c++ {
		if results[c] {
			successfulTests = successfulTests + 1
		}
	}

    printf("%d tests were performed\n", len(results))
    printf("%d were successful\n", successfulTests)
    printf("%d failed\n", len(results) - successfulTests)
}

bool Type Functions

bool.print

bool.eq

bool.uneq

bool.not

bool.or

bool.and

Example

package main

func main () {
	bool.print(bool.eq(true, true))
	bool.print(bool.uneq(false, true))
	bool.print(bool.not(false))
	bool.print(bool.or(true, false))
	bool.print(bool.and(true, true))
}

str Type Functions

str.print

str.concat

Example

package main

func main () {
	str.print(str.concat("Hello, ", "World!"))
}

i32 Type Functions

The following functions are of general purpose and are restricted to work with data structures of type i32 where it makes sense.

i32.print

i32.add

i32.sub

i32.mul

i32.div

i32.mod

i32.abs

Example

package main

func main () {
	i32.print(i32.add(5, 7))
	i32.print(i32.sub(6, 3))
	i32.print(i32.mul(4, 8))
	i32.print(i32.div(15, 3))
	i32.print(i32.mod(5, 3))
	i32.print(i32.abs(-13))
}

i32.log

i32.log2

i32.log10

i32.pow

i32.sqrt

Example

package main

func main () {
	i32.print(i32.log(13))
	i32.print(i32.log2(3))
	i32.print(i32.log10(12))
	i32.print(i32.pow(4, 4))
	i32.print(i32.sqrt(2))
}

i32.gt

i32.gteq

i32.lt

i32.lteq

i32.eq

i32.uneq

Example

package main

func main () {
	bool.print(i32.gt(5, 3))
	bool.print(i32.gteq(3, 8))
	bool.print(i32.lt(4, 3))
	bool.print(i32.lteq(8, 6))
	bool.print(i32.eq(-9, -9))
	bool.print(i32.uneq(3, 3))
}

i32.bitand

i32.bitor

i32.bitxor

i32.bitclear

i32.bitshl

i32.bitshr

Example

package main

func main () {
	i32.print(i32.bitand(2, 5))
	i32.print(i32.bitor(8, 3))
	i32.print(i32.bitxor(3, 9))
	i32.print(i32.bitclear(4, 4))
	i32.print(i32.bitshl(5, 9))
	i32.print(i32.bitshr(1, 6))
}

i32.max

i32.min

Example

package main

func main () {
	i32.print(i32.max(2, 5))
	i32.print(i32.min(10, 3))
}

i32.rand

Example

package main

func main () {
	i32.print(i32.rand(0, 100))
}

i64 Type Functions

The following functions are of general purpose and are restricted to work with data structures of type i64 where it makes sense.

i64.print

i64.add

i64.sub

i64.mul

i64.div

i64.mod

i64.abs

Example

package main

func main () {
	i64.print(i64.add(5L, 7L))
	i64.print(i64.sub(6L, 3L))
	i64.print(i64.mul(4L, 8L))
	i64.print(i64.div(15L, 3L))
	i64.print(i64.mod(5L, 3L))
	i64.print(i64.abs(-13L))
}

i64.log

i64.log2

i64.log10

i64.pow

i64.sqrt

Example

package main

func main () {
	i64.print(i64.log(13L))
	i64.print(i64.log2(3L))
	i64.print(i64.log10(12L))
	i64.print(i64.pow(4L, 4L))
	i64.print(i64.sqrt(2L))
}

i64.gt

i64.gteq

i64.lt

i64.lteq

i64.eq

i64.uneq

Example

package main

func main () {
	bool.print(i64.gt(5L, 3L))
	bool.print(i64.gteq(3L, 8L))
	bool.print(i64.lt(4L, 3L))
	bool.print(i64.lteq(8L, 6L))
	bool.print(i64.eq(-9L, -9L))
	bool.print(i64.uneq(3L, 3L))
}

i64.bitand

i64.bitor

i64.bitxor

i64.bitclear

i64.bitshl

i64.bitshr

Example

package main

func main () {
	i64.print(i64.bitand(2L, 5L))
	i64.print(i64.bitor(8L, 3L))
	i64.print(i64.bitxor(3L, 9L))
	i64.print(i64.bitclear(4L, 4L))
	i64.print(i64.bitshl(5L, 9L))
	i64.print(i64.bitshr(1L, 6L))
}

i64.max

i64.min

Example

package main

func main () {
	i64.print(i64.max(2L, 5L))
	i64.print(i64.min(10L, 3L))
}

i64.rand

Example

package main

func main () {
	i64.print(i64.rand(0L, 100L))
}

f32 Type Functions

The following functions are of general purpose and are restricted to work with data structures of type f32 where it makes sense.

f32.print

f32.add

f32.sub

f32.mul

f32.div

f32.abs

Example

package main

func main () {
	f32.print(f32.add(5.3, 10.5))
	f32.print(f32.sub(3.2, 6.7))
	f32.print(f32.mul(-7.9, -7.1))
	f32.print(f32.div(10.3, 2.4))
	f32.print(f32.abs(-3.14159))
}

f32.log

f32.log2

f32.log10

f32.pow

f32.sqrt

Example

package main

func main () {
	f32.print(f32.log(2.3))
	f32.print(f32.log2(3.4))
	f32.print(f32.log10(3.0))
	f32.print(f32.pow(-5.3, 2.0))
	f32.print(f32.sqrt(4.0))
}

f32.sin

f32.cos

Example

package main

func main () {
	f32.print(f32.sin(1.0))
	f32.print(f32.cos(2.0))
}

f32.gt

f32.gteq

f32.lt

f32.lteq

f32.eq

f32.uneq

Example

package main

func main () {
	bool.print(f32.gt(5.3, 3.1))
	bool.print(f32.gteq(3.7, 1.9))
	bool.print(f32.lt(2.4, 5.5))
	bool.print(f32.lteq(8.4, 3.2))
	bool.print(f32.eq(10.3, 10.3))
	bool.print(f32.uneq(8.9, 3.3))
}

f32.max

f32.min

Example

package main

func main () {
	f32.print(f32.max(3.3, 4.2))
	f32.print(f32.min(5.8, 9.9))
}

f64 Type Functions

The following functions are of general purpose and are restricted to work with data structures of type f64 where it makes sense.

f64.print

f64.add

f64.sub

f64.mul

f64.div

f64.abs

Example

package main

func main () {
	f64.print(f64.add(5.3D, 10.5D))
	f64.print(f64.sub(3.2D, 6.7D))
	f64.print(f64.mul(-7.9D, -7.1D))
	f64.print(f64.div(10.3D, 2.4D))
	f64.print(f64.abs(-3.14159D))
}

f64.log

f64.log2

f64.log10

f64.pow

f64.sqrt

Example

package main

func main () {
	f64.print(f64.log(2.3D))
	f64.print(f64.log2(3.4D))
	f64.print(f64.log10(3.0D))
	f64.print(f64.pow(-5.3D, 2.0D))
	f64.print(f64.sqrt(4.0D))
}

f64.sin

f64.cos

Example

package main

func main () {
	f64.print(f64.sin(1.0D))
	f64.print(f64.cos(2.0D))
}

f64.gt

f64.gteq

f64.lt

f64.lteq

f64.eq

f64.uneq

Example

package main

func main () {
	bool.print(f64.gt(5.3D, 3.1D))
	bool.print(f64.gteq(3.7D, 1.9D))
	bool.print(f64.lt(2.4D, 5.5D))
	bool.print(f64.lteq(8.4D, 3.2D))
	bool.print(f64.eq(10.3D, 10.3D))
	bool.print(f64.uneq(8.9D, 3.3D))
}

f64.max

f64.min

Example

package main

func main () {
	f64.print(f64.max(3.3D, 4.2D))
	f64.print(f64.min(5.8D, 9.9D))
}

time Package Functions

The functions in the time package deal with real-time in your programs. They are used to measure and stop time. Note that in order to use these functions you need to import the time package.

time.Sleep

time.UnixMilli

time.UnixNano

Example

package main
import "time"

func main () {
	var start i64
	var end i64

	start = time.UnixMilli()
	time.Sleep(1000)
	end = time.UnixMilli()

	printf("elapsed time in milliseconds: \t%d\n", end - start)

	start = time.UnixNano()
	time.Sleep(1000)
	end = time.UnixNano()

	printf("elapsed time in nanoseconds: \t%d\n", end - start)
}

os Package Functions

The os package provides functions that serve as an interface to CX's underlaying operating system.

os.GetWorkingDirectory

os.Open

os.Close

Example

package main
import "os"

func main () {
	var wd str
	wd = os.GetWorkingDirectory()

	var fileName str
	fileName = str.concat(wd, "testing.cx")

	os.Open(fileName)
	os.Close(fileName)
}

gl Package Functions

"OpenGL is the premier environment for developing portable, interactive 2D and 3D graphics applications. Since its introduction in 1992, OpenGL has become the industry's most widely used and supported 2D and 3D graphics application programming interface (API), bringing thousands of applications to a wide variety of computer platforms. OpenGL fosters innovation and speeds application development by incorporating a broad set of rendering, texture mapping, special effects, and other powerful visualization functions. Developers can leverage the power of OpenGL across all popular desktop and workstation platforms, ensuring wide application deployment." This description was extracted from OpenGL's website (https://www.opengl.org/).

gl.ActiveTexture

gl.AttachShader

gl.Begin

gl.BindAttribLocation

gl.BindBuffer

gl.BindFramebuffer

gl.BindTexture

gl.BindVertexArray

gl.BlendFunc

gl.BufferData

gl.BufferSubData

gl.CheckFramebufferStatus

gl.ClearColor

gl.ClearDepth

gl.Clear

gl.Color3f

gl.Color4f

gl.CompileShader

gl.CreateProgram

gl.CreateShader

gl.CullFace

gl.DeleteBuffers

gl.DeleteFramebuffers

gl.DeleteProgram

gl.DeleteShader

gl.DeleteTextures

gl.DeleteVertexArrays

gl.DepthFunc

gl.DepthMask

gl.DetachShader

gl.Disable

gl.DrawArrays

gl.EnableClientState

gl.EnableVertexAttribArray

gl.Enable

gl.End

gl.FramebufferTexture2D

gl.Free

gl.Frustum

gl.GenBuffers

gl.GenFramebuffers

gl.GenTextures

gl.GenVertexArrays

gl.GetAttribLocation

gl.GetError

gl.GetShaderiv

gl.GetTexLevelParameteriv

gl.Hint

gl.Init

gl.Lightfv

gl.LinkProgram

gl.LoadIdentity

gl.MatrixMode

gl.NewTexture

gl.Normal3f

gl.Ortho

gl.PopMatrix

gl.PushMatrix

gl.Rotatef

gl.Scalef

gl.ShaderSource

gl.Strs

gl.TexCoord2d

gl.TexCoord2f

gl.TexEnvi

gl.TexImage2D

gl.TexParameteri

gl.Translatef

gl.Uniform1f

gl.Uniform1i

gl.UseProgram

gl.Vertex2f

gl.Vertex3f

gl.VertexAttribPointerI32

gl.VertexAttribPointer

gl.Viewport

gl.getUniformLocation

glfw Package Functions

"GLFW is an Open Source, multi-platform library for OpenGL, OpenGL ES and Vulkan development on the desktop. It provides a simple API for creating windows, contexts and surfaces, receiving input and events." This description was extracted from GLFW's website (https://www.glfw.org/).

glfw.CreateWindow

glfw.GetCursorPos

glfw.GetFramebufferSize

glfw.GetTime

glfw.Init

glfw.MakeContextCurrent

glfw.PollEvents

glfw.SetCursorPosCallback

glfw.SetInputMode

glfw.SetKeyCallback

glfw.SetMouseButtonCallback

glfw.SetShouldClose

glfw.SetWindowPos

glfw.ShouldClose

glfw.SwapBuffers

glfw.SwapInterval

glfw.WindowHint

gltext Package Functions

"The gltext package offers a simple set of text rendering utilities for OpenGL programs. It deals with TrueType and Bitmap (raster) fonts. Text can be rendered in various directions (Left-to-right, right-to-left and top-to-bottom). This allows for correct display of text for various languages." This description was extracted from gltext's website (https://github.com/go-gl/gltext).

The gltext functions can be used to display character strings on windows. Different fonts can be used by loading font files using gltext.LoadTrueType.

gltext.GlyphBounds () (i32, i32)

gltext.LoadTrueType (str, str, i32, i32, i32, i32) ()

gltext.Metrics (str, str) (i32, i32)

gltext.NextRune (str, str, i32) (i32, i32, i32, i32, i32, i32, i32)

gltext.Printf

gltext.Texture

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