Introduction. #
Cyber is a fast, efficient, and concurrent scripting language. The landing page is at cyberscript.dev and contains performance metrics and release notes.
These docs provide a reference manual for the language. You can read it in order or jump around using the navigation. You may come across features that are marked Incomplete
or Planned
. This is because the docs are written as if all features have been completed already.
Type System. #
Cyber is a statically typed language so the documentation will provide examples using typed syntax. However, dynamic typing is also supported with a less restrictive syntax. If you're coming from a language such as Python, JavaScript, or Lua, it can be easier to get started with Dynamic Typing.
^topicHello World. #
use math
var worlds = ['World', '世界', 'दुनिया', 'mundo']
worlds.append(math.random())
for worlds -> w:
print "Hello, $(w)!"
^topic
Syntax. #
Cyber's syntax is concise and easy to read.
Statements. #
A statement ends with the new line:
var a = 123
To wrap a statement to the next line, the last token before the new line must be an operator or a separator:
var gameover = health <= 0 or
player.collidesWith(spikes)
if year > 2020 and year <= 2030 and
month > 0 and month <= 11:
print 'Valid'
Any token inside a delimited syntax (such as parentheses or brackets) can be wrapped to the next line:
var sum = add(1, 2, 3, 4,
100, 200, 300, 400)
var colors = ['red', 'blue', 'green',
'purple', 'orange', 'yellow']
^topic
Blocks. #
Some statements can start a new block with a colon. The first statement in a new block must be indented further. Spaces or tabs can be used for indentation but not both.
-- This `if` statement begins a new block.
if true:
var a = 234
Subsequent statements in the block must follow the same indentation. The block ends when a statement recedes from this indentation:
var items = [10, 20, 30]
for items -> it:
if it == 20:
print it
print it -- This is the first statement outside of the `if` block.
Compact blocks allow only one statement after the starting block:
-- A single line block.
if true: print 123
if true: print 123
-- This is an indentation error since the compact block is already consumed.
print 234
Since blocks require at least one statement, use pass
as a placeholder statement:
func foo():
pass
^topic
Variables. #
Variables allow values to be stored into named locations in memory.
Local variables and static variables are supported.
^topicLocal variables. #
Local variables exist until the end of their scope.
They are declared and initialized using the var
keyword:
var a = 123
When declared without a type specifier next to the variable, the type is inferred from the right initializer. In the above example, the variable a
is initialized with the type int
.
Variables can be assigned afterwards using the =
operator:
a = 234
^topic
Explicit type constraint. #
When a type specifier is provided, the value assigned to the variable must satisfy the type constraint or a compile error is reported:
var a float = 123.0
var b int = 123.0 --> CompileError. Expected `int`, got `float`.
Any operation afterwards that violates the type constraint of the variable will result in a compile error
a = 'hello' --> CompileError. Expected `float`, got `String`.
^topic
Variable scopes. #
Blocks create a new variable scope. Variables declared in the current scope will take precedence over any parent variables with the same name:
func foo():
var a = 234
if true:
var a = 345 -- New `a` declared.
print a --> 345
print a --> 234
^topic
Static variables. #
Static variables live until the end of the script. They act as global variables and are visible from anywhere in the script.
Static variables are declared with var
like local variables, but a namespace must be provided before the variable name:
var .a = 123
func foo():
print a --> 123
The .
prefix is used to reference the current module's namespace.
Unlike local variables, static variables do not currently infer the type from the right hand side so a specific type must be specified or it will default to the any
type:
var .my_map Map = Map{}
Since static variables are initialized outside of a fiber's execution flow, they can not reference any local variables:
var .b = a --> Compile error, initializer can not reference a local variable.
-- Main execution.
var a = 123
However, they can be reassigned after initialization:
var .b = 0
var a = 123
b = a -- Reassigning after initializing.
Static variable initializers have a natural order based on when it was encountered by the compiler. In the case of imported variables, the order of the import would affect this order. The following would print '123' before '234':
var .a = print(123)
var .b = print(234)
When the initializers reference other static variables, those child references are initialized first in DFS order and supersede the natural ordering. The following initializes b
before a
.
var .a = b + 321
var .b = 123
print a --> 444
Circular references in initializers are not allowed. When initialization encounters a reference that creates a circular dependency an error is reported.
var .a = b
var .b = a --> CompileError. Referencing `a` creates a circular dependency.
Sometimes, you may want to initialize a static variable by executing multiple statements in order. For this use case, you can use a declaration block. Planned Feature
var .myImage =:
var img = loadImage('me.png')
img.resize(100, 100)
img.filter(.blur, 5)
break img
The final resulting value that is assigned to the static variable is provided by a break
statement. If a break
statement is not provided, none
is assigned instead.
use $global
#
When use $global
is declared in the module, it allows the use of undeclared variables:
use $global
a = 123
print a --> 123
Accessing an undeclared variable before it's initialized results in a runtime error:
use $global
print a --> panic: `a` is not defined in `$global`.
^topic
Reserved identifiers. #
^topicKeywords. #
There are 28
general keywords. This list categorizes them:
- Control Flow:
if
else
switch
case
while
for
break
continue
pass
- Operators:
or
and
not
- Variables:
var
- Functions:
func
return
- Coroutines:
coinit
coyield
coresume
- Types:
type
as
- Type embedding:
use
- Metaprogramming:
template
- Error Handling:
try
catch
throw
- Modules:
use
module
- Dynamic Typing:
let
Contextual keywords. #
These keywords only have meaning in a certain context.
^topicLiterals. #
- Booleans:
true
false
- Error Values:
error
- None:
none
Operators. #
Cyber supports the following operators. They are ordered from highest to lowest precedence.
Operator | Description |
---|---|
<< >> | Bitwise left shift, right shift. |
& | Bitwise and. |
| || | Bitwise or, exclusive or. |
^ | Power. |
/ % * | Division, modulus, multiplication. |
+ - | Addition, subtraction. |
as | Type casting. |
> >= < <= != == | Greater, greater or equal, less, less or equal, not equals, equals. |
and | Logical and. |
or | Logical or. |
.. -.. | Range, reversed range. |
Arithmetic Operators. #
The following arithmetic operators are supported for the numeric data types.
1 + 2 -- Addition, evaluates to 3.
100 - 10 -- Subtraction, evaluates to 90.
3 * 4 -- Multiplication, evaluates to 12.
20 / 5 -- Division, evaluates to 4.
2 ^ 4 -- Raise to the power, evaluates to 16.
12 % 5 -- Modulus remainder, evaluates to 2.
-(10) -- Apply negative, evaluates to -10.
^topic
Comparison Operators. #
Cyber supports the following comparison operators. By default, a comparison operator evaluates to a Boolean value.
The equals operator returns true if the two values are equal. For primitive types, the comparison checks the types and the underlying value. For strings, the underlying bytes are compared for equality. For objects, the comparison checks that the two values reference the same object.
1 == 1 -- Evaluates to `true`
1 == 2 -- Evaluates to `false`
1 == true -- Evaluates to `false`
var a = 'abc'
a == 'abc' -- Evaluates to `true`
a = []
var b = a
a == b -- Evaluates to `true`
a == [] -- Evaluates to `false`
The not equals operator returns true if the two values are not equal.
1 != 1 -- Evaluates to `false`
1 != 2 -- Evaluates to `true`
Number types have additional comparison operators.
a > b -- `true` if a is greater than b
a >= b -- `true` if a is greater than or equal to b
a < b -- `true` if a is less than b
a <= b -- `true` if a is less than or equal to b
^topic
Logic Operators. #
The logical operators and
, or
, and not
are supported.
and
evaluates to true
if both operands are true
. Otherwise, it evaluates to false
. If the left operand is false
, the evaluation of the right operand is skipped:
true and true --> true
true and false --> false
false and true --> false
false and false --> false
or
evaluates to true
if at least one of the operands is true
. Otherwise, it evaluates to false
. If the left operand is true
, the evaluation of the right operand is skipped:
true or true --> true
true or false --> true
false or true --> true
false or false --> false
The unary operator not
performs negation on the boolean value. The unary operator !
can also be used instead of not
.
not false --> true
not true --> false
!false --> true
!true --> false
^topic
Bitwise Operators. #
The following bitwise operators are supported for int
number values.
-- Bitwise and: any underlying bits that are set in both integers are set in the new integer.
a & b
-- Bitwise or: any underlying bits that are set in either integer a or integer b are set in the new integer.
a | b
-- Bitwise exclusive or: any underlying bits that are set in either integer a or integer b but not both are set in the new integer.
a || b
-- Bitwise right shift: a's bits are shifted b bits to the least significant end. This performs sign-extension on the 32-bit integer.
a >> b
-- Bitwise left shift: a's bits are shifted b bits to the most significant end. This does not perform sign-extension on the 32-bit integer.
a << b
-- Bitwise not: a's integer bits are flipped.
~a
^topic
Operator overloading. #
See Operator overloading in Metaprogramming.
^topicZero values. #
Uninitialized type fields currently default to their zero values. However, this implicit behavior will be removed in the future in favor of a default value clause. Zero values must then be expressed using the reserved zero
literal.
The following shows the zero values of builtin or created types:
Type | Zero value |
---|---|
boolean | false |
int | 0 |
float | 0.0 |
String | '' |
Array | Array('') |
List | [] |
Map | Map{} |
type S | S{} |
#host type S | S.$zero() |
dynamic | int(0) |
any | int(0) |
?S | Option(S).none |
Type casting. #
The as
keyword can be used to cast a value to a specific type. Casting lets the compiler know what the expected type is and does not perform any conversions.
If the compiler knows the cast will always fail at runtime, a compile error is returned instead.
print('123' as int) --> CompileError. Can not cast `String` to `int`.
If the cast fails at runtime, a panic is returned.
var erased any = 123
add(1, erased as int) --> Success.
print(erased as String) --> panic: Can not cast `int` to `String`.
func add(a int, b int):
return a + b
^topic
Comments. #
A single line comment starts with two hyphens and ends at the end of the line.
-- This is a comment.
var a = 123 -- This is a comment on the same line as a statement.
There will be multi-line comments in Cyber but the syntax has not been determined.
^topicCYON. #
CYON or the Cyber object notation is similar to JSON. The format uses the same literal value semantics as Cyber.
{
name: 'John Doe',
'age': 25,
-- This is a comment
cities: [
'New York',
'San Francisco',
'Tokyo',
],
}
^topic
Basic Types. #
In Cyber, there are primitive types and object types. By default, primitives are copied around by value and don't need additional heap memory or reference counts.
Primitives include Booleans, Floats, Integers, Enums, Symbols, and Error Values.
Object types include Lists, Tuples, Maps, Strings, Arrays, Objects, Lambdas, Fibers, Choices, Optionals, Pointers, and several internal object types.
Booleans. #
Booleans can be true
or false
. See type bool
.
var a = true
if true:
print 'a is true'
^topic
Numbers. #
^topicIntegers. #
int
is the default integer type. It has 48-bits and can represent integers in the range -(247) to 247-1. See type int
.
When a numeric literal is used and the type can not be inferred, it will default to the int
type:
var a = 123
Integer notations always produce a int
value:
var a = 0xFF -- hex.
a = 0o17 -- octal.
a = 0b1010 -- binary.
a = `🐶` -- UTF-8 rune.
Arbitrary values can be converted to a int
using the type as a function.
var a = '123'
var b = int(a)
In addition to arithmetic operations, integers can also perform bitwise operations.
^topicFloats. #
float
is the default floating point type. It has a (IEEE 754) 64-bit floating point format. See type float
.
Although a float
represents a decimal number, it can also represent integers between -(253-1) and (253-1). Any integers beyond the safe integer range is not guaranteed to have a unique representation.
A numeric literal can be used to create a float
if the inferred type is a float
:
var a float = 123
Decimal and scientific notations always produce a float
value:
var a = 2.34567
var b = 123.0e4
Arbitrary values can be converted to a float
using the type as a function.
var a = '12.3'
var b = float(a)
^topic
Big Numbers. #
^topicPlanned Feature
Strings. #
The String
type represents a sequence of UTF-8 codepoints. Each code point is stored internally as 1-4 bytes. See type String
.
Strings are not validated by default. If the codepoint is invalid at a particular index, the replacement character (0xFFFD) is returned instead.
Strings are immutable, so operations that do string manipulation return a new string. By default, short strings are interned to reduce memory footprint.
Under the hood, there are multiple string implementations to make operations faster by default using SIMD.
^topicRaw string literal. #
A raw string doesn't allow any escape sequences or string interpolation.
Single quotes are used to delimit a single line literal:
var fruit = 'apple'
var str = 'abc🦊xyz🐶'
Since raw strings interprets the sequence of characters as is, a single quote character can not be escaped:
var fruit = 'Miso's apple' -- ParseError.
Triple single quotes are used to delimit a multi-line literal. It also allows single quotes and double single quotes in the string:
var fruit = '''Miso's apple'''
var greet = '''Hello
World'''
^topic
String literal. #
A string literal allows escape sequences and string interpolation.
Double quotes are used to delimit a single line literal:
var fruit = "apple"
var sentence = "The $(fruit) is tasty."
var doc = "A double quote can be escaped: \""
Triple double quotes are used to delimit a multi-line literal:
var title = "last"
var doc = """A double quote " doesn't need to be escaped."""
var str = """line a
line "b"
line $(title)
"""
^topic
Escape sequences. #
The following escape sequences are supported in string literals wrapped in double quotes:
Sequence | Code | Character |
---|---|---|
\0 | 0x00 | Null |
\a | 0x07 | Terminal bell |
\b | 0x08 | Backspace |
\e | 0x1b | Escape |
\n | 0x0a | Line feed |
\r | 0x0d | Carriage return |
\t | 0x09 | Horizontal tab |
\" | 0x22 | Double quote |
\\ | 0x5c | Backslash |
\x?? | -- | Hex number |
Example:
print "\xF0\x9F\x90\xB6" --> 🐶
^topic
String indexing. #
The index operator returns the rune starting at the given byte index:
var a = 'abcxyz'
print a[1] --> 98
print(a[1] == `b`) --> true
If an index does not begin a sequence of valid UTF-8 bytes, the replacement character (0xFFFD, 65533) is returned:
var a = '🐶abcxyz'
print a[1] --> 65533
Since indexing operates at the byte level, it should not be relied upon for iterating runes or rune indexing. However, if the string is known to only contain ASCII runes (each rune occupies one byte), indexing will return the expected rune.
String.seek
will always return the correct byte index for a rune index:
var a = '🐶abcxyz'
print a.seek(2) --> 5
print a[a.seek(2)] --> 98 (`b`)
Similarily, slicing operates on byte indexes. Using the slice operator will return a view of the string at the given start and end (exclusive) indexes. The start index defaults to 0 and the end index defaults to the string's byte length:
var str = 'abcxyz'
var sub = str[0..3]
print str[0..3] --> abc
print str[..5] --> abcxy
print str[1..] --> bcxyz
^topic
String concatenation. #
Concatenate two strings together with the +
operator or the method concat
.
var res = 'abc' + 'xyz'
res = res.concat('end')
^topic
String interpolation. #
Expressions can be embedded into string templates with $()
:
var name = 'Bob'
var points = 123
var str = "Scoreboard: $(name) $(points)"
String templates can not contain nested string templates.
^topicString formatting. #
Values that can be formatted into a string will have a fmt
method:
var file = os.openFile('data.bin', .read)
var bytes = file.readToEnd()
-- Dump contents in hex.
print "$(bytes.fmt(.x))"
^topic
Line-join literal. #
The line-join literal joins string literals with the new line character \n
. Planned Feature
This has several properties:
- Ensures the use of a consistent line separator:
\n
- Allows lines to have a mix of raw string or string literals.
- Single quotes and double quotes do not need to be escaped.
- Allows each line to be indented along with the surrounding syntax.
- The starting whitespace for each line is made explicit.
var paragraph = [
\'the line-join literal
\'hello\nworld
\"hello $(name)
\'last line
\'
]
^topic
Mutable strings. #
To mutate an existing string, use type MutString. Planned Feature
^topicArrays. #
An Array
is an immutable sequence of bytes.
See type Array
.
var a = Array('abcd')
a = a.insertByte(1, 255)
print a[0] -- "97"
print a[1] -- "255"
^topic
Lists. #
Lists are a builtin type that holds an ordered collection of elements. Lists grow or shrink as you insert or remove elements. See type List
.
-- Construct a new list.
var list = [1, 2, 3]
-- The first element of the list starts at index 0.
print list[0] -- Prints '1'
Lists can be sliced with the range ..
clause. The sliced list becomes a new list that you can modify without affecting the original list. The end index is non-inclusive.
var list = [ 1, 2, 3, 4, 5 ]
list[0..0] -- []
list[0..3] -- [ 1, 2, 3 ]
list[3..] -- [ 4, 5 ]
list[..3] -- [ 1, 2, 3 ]
The +..
invokes the slice operator with an end position that is an increment from the start: Planned Feature
var list = [ 1, 2, 3, 4, 5 ]
list[2+..2] -- [ 3, 4 ]
List operations.
var list = [234]
-- Append a value.
list.append(123)
-- Inserting a value at an index.
list.insert(1, 345)
-- Get the length.
print list.len() -- Prints '2'
-- Sort the list in place.
list.sort((a, b) => a < b)
-- Iterating a list.
for list -> it:
print it
-- Remove an element at a specific index.
list.remove(1)
^topic
Tuples. #
^topicIncomplete: Tuples can only be created from #host funcs at the moment.
Tables. #
A Table
is a versatile object that can have an arbitrary set of fields.
By default, the record literal initializes a Table
:
var o = {}
o = {a: 123}
print o.a --> 123
A Table
can be initialized explicitly using its type name:
var o = Table{a: 123}
Any field can be assigned a value. However, accessing a field before it's initialized results in a panic:
o.my_field = 234
print o.my_field --> 234
print o.foo --> panic: The field `foo` was not initialized.
^topic
Table indexing. #
Indexing can be used to access a dynamic field or an arbitrary key:
var o = { name: 'Nova' }
var field = 'name'
print o[field] --> Nova
o[10] = [1, 2, 3]
print o[10] --> List (3)
If the key is not an identifier string, the value can only be obtained through indexing.
^topicCheck field existence. #
^topicPlanned Feature
Prototypes. #
^topicPlanned Feature
Maps. #
Maps are a builtin type that store key value pairs in dictionaries. See type Map
.
Maps are initialized with the Map
type and a record literal:
var map = Map{ a: 123, b: () => 5 }
The empty record literal creates an empty map:
var empty = Map{}
^topic
Map indexing. #
Get a value from the map using the index operator:
print map['a']
^topic
Map operations. #
var map = Map{}
-- Set a key value pair.
map[123] = 234
-- Get the size of the map.
print map.size()
-- Remove an entry by key.
map.remove(123)
-- Iterating a map.
for map -> [val, key]:
print "$(key) -> $(val)"
^topic
Map block. #
Entries can also follow a collection literal block. This gives structure to the entries and has the added benefit of allowing multi-line lambdas. Most likely this will not be implemented in favor of a builder syntax
var colors = {}:
red: 0xFF0000
green: 0x00FF00
blue: 0x0000FF
dump func (c):
print c.red
print c.green
print c.blue
-- Nested map.
darker {}:
red: 0xAA0000
green: 0x00AA00
blue: 0x0000AA
^topic
Symbols. #
Symbol literals begin with .
, followed by an identifier. They have their own global unique id.
var currency = .usd
print(currency == .usd) -- 'true'
print int(currency) -- '123' or some arbitrary id.
^topic
any
. #
Unlike dynamic
, any
is statically typed and performs type checks at compile-time.
any
type can hold any value, but copying it to narrowed type destination will result in a compile error:
func square(i int):
return i * i
var a any = 123
a = ['a', 'list'] --> Valid assignment to a value with a different type.
a = 10
print square(a) --> CompileError. Expected `int`, got `any`.
a
must be explicitly casted to satisfy the type constraint:
print square(a as int) --> 100
^topic
dynamic
. #
The dynamic type defers type checking to runtime. However, it also tracks its own recent type in order to surface errors at compile-time. See Dynamic Typing.
^topicCustom Types. #
Objects. #
An object type contains field and function members. New instances can be created from them similar to a struct or class in other languages. Unlike classes, there is no builtin concept of inheritance but a similar effect can be achieved using composition and embedding.
Object types are declared with type object
. The object
keyword is optional when using a type
declaration. These two declarations are equivalent:
type A object:
my_field int
type A:
my_field int
Fields must be declared at the top of the type
block with their names and type specifiers:
type Node:
value int
next ?Node
^topic
Instantiate. #
New object instances are created using a record literal with a leading type name:
var node = Node{value: 123, next: none}
print node.value -- Prints "123"
A record literal can also initialize to the inferred object type:
var node Node = {value: 234, next: none}
print node.value -- Prints "234"
^topic
Field visibility. #
All fields have public visibility. However, when a field is declared with a -
prefix, it suggests that it should not be made available to an editor's autocomplete:
type Info:
a int
-b int
-secret String
^topic
Default field values. #
When a field is omitted in the record literal, it gets initialized to its zero value:
var node Node = {value: 234}
print node.next -- Prints "Option.none"
type Student:
name String
age int
gpa float
var s = Student{}
print s.name -- Prints ""
print s.age -- Prints "0"
print s.gpa -- Prints "0.0"
^topic
Circular references. #
Circular type references are allowed if the object can be initialized:
type Node:
val any
next ?Node
var n = Node{} -- Initializes.
In this example, next
has an optional ?Node
type so it can be initialized to none
when creating a new Node
object.
The following example will fail because this version of Node
can not be initialized:
type Node:
val any
next Node
var n = Node{} -- CompileError. Can not zero initialize `next`
-- because of circular dependency.
^topic
Unnamed object. #
Unnamed object types can be declared and used without an explicit type
declaration:
type Node:
value object:
a int
b float
next ?Node
var node = Node{
value: {a: 123, b: 100.0},
next: none,
}
^topic
Methods. #
Methods allow invoking a function on an object instance using the .
operator:
type Node:
value int
next ?Node
func inc(n):
value += n
func incAndPrint():
self.inc(321)
print value
var n = Node{value: 123, next: none}
n.incAndPrint() -- Prints "444"
Methods can be declared outside of the type declaration. When using the flat declaration style, self
must be the first parameter to distinguish it from a type function:
func Node.getNext(self):
return self.next
^topic
self
variable. #
Type members can be implicitly referenced inside the method. Incomplete: Only the type's fields can be referenced this way.
To reference members explicitly inside a method, use the builtin self
:
type Node:
value int
next ?Node
func double():
return self.value * 2
^topic
Type functions. #
Type functions are declared outside of the type
block with an explicit namespace path:
type Node:
value int
next ?Node
-- Declare static function inside `Node`.
func Node.new():
return Node{value: 123, next: none}
var n = Node.new()
^topic
Type variables. #
Similarily, type variables are declared outside of the type
block:
-- Declare inside the `Node` namespace.
var Node.DefaultValue = 100
print Node.DefaultValue -- Prints "100"
^topic
Type embedding. #
Type embedding facilitates type composition by using the namespace of a child field's type: Planned Feature
type Base:
a int
func double() int:
return a * 2
type Container:
b use Base
var c = Container{b: Base{a: 123}}
print c.a --> 123
print c.double() --> 246
Note that embedding a type does not declare extra fields or methods in the containing type. It simply augments the type's using namespace by binding the embedding field.
If there is a member name conflict, the containing type's member has a higher precedence:
type Container:
a int
b use Base
var c = Container{a: 999, b: Base{a: 123}}
print c.a --> 999
print c.double() --> 246
Since the embedding field is named, it can be used just like any other field:
print c.b.a --> 123
^topic
Structs. #
Struct types can contain field and method members just like object types, but their instances are copied by value rather than by reference. In that sense, they behave like primitive data types.
Unlike objects, structs do not have a reference count. They can be safely referenced using borrow semantics. Unsafe pointers can also reference structs.
^topicDeclare struct. #
Struct types are created using the type struct
declaration:
type Vec2 struct:
x float
y float
var v = Vec2{x: 30, y: 40}
^topic
Copy structs. #
Since structs are copied by value, assigning a struct to another variable creates a new struct:
var v = Vec2{x: 30, y: 40}
var w = v
v.x = 100
print w.x -- Prints '30'
print v.x -- Prints '100'
^topic
Enums. #
A new enum type can be declared with the type enum
declaration.
An enum value can only be one of the unique symbols declared in the enum type.
By default, the symbols generate unique ids starting from 0.
type Fruit enum:
case apple
case orange
case banana
case kiwi
var fruit = Fruit.kiwi
print fruit -- 'Fruit.kiwi'
print int(fruit) -- '3'
When the type of the value is known to be an enum, it can be assigned using a symbol literal.
var fruit = Fruit.kiwi
fruit = .orange
print(fruit == Fruit.orange) -- 'true'
^topic
Choices. #
Choices are enums with payloads (also known as sum types or tagged unions). An enum declaration becomes a choice type if one of the cases has a payload type specifier:
type Shape enum:
case rectangle Rectangle
case circle object:
radius float
case triangle object:
base float
height float
case line float
case point
type Rectangle:
width float
height float
^topic
Initialize choice. #
If the payload is an object type, the choice can be initialized with a simplified record literal:
var s = Shape.rectangle{width: 10, height: 20}
The general way to initialize a choice is to pass the payload as an argument:
var rect = Rectangle{width: 10, height: 20}
var s = Shape{rectangle: rect}
s = Shape{line: 20}
A choice without a payload is initialized with an empty record literal:
var s = Shape.point{}
^topic
Choice switch
. #
case
clauses can match choices and capture the payload:
switch s
case .rectangle -> r:
print "$(r.width) $(r.height)"
case .circle -> c:
print "$(c.radius)"
case .triangle -> t:
print "$(t.base) $(t.height)"
case .line -> len:
print "$(len)"
case .point:
print "a point"
else:
print "Unsupported."
^topic
Access choice. #
A choice can be accessed by specifying the access operator .!
before the tagged member name. This will either return the payload or panic at runtime: Planned Feature
var s = Shape{line: 20}
print s.!line -- Prints '20'
^topic
Optionals. #
Optionals provide Null Safety by forcing values to be unwrapped before they can be used.
The generic Option
type is a choice type that either holds a none
value or contains some
value. The option template is defined as:
template(T type)
type Option enum:
case none
case some #T
A type prefixed with ?
is the idiomatic way to create an option type. The following String optional types are equivalent:
Option(String)
?String
^topic
Wrap value. #
A value is automatically wrapped into the inferred optional's some
case:
var a ?String = 'abc'
print a --> some(abc)'
^topic
Wrap none
. #
none
is automatically initialized to the inferred optional's none
case:
var a ?String = none
print a --> none
^topic
Unwrap or panic. #
The .?
access operator is used to unwrap an optional. If the expression evaluates to the none
case, the runtime panics:
var opt ?int = 123
var v = opt.?
print v --> 123
^topic
Unwrap or default. #
The ?else
control flow operator either returns the unwrapped value or a default value when the optional is none
:
var opt ?int = none
var v = opt ?else 123
print v --> 123
?else
can be used in an assignment block: Planned Feature
var v = opt ?else:
break 'empty'
var v = opt ?else:
throw error.Missing
^topic
Optional chaining. #
Given the last member's type T
in a chain of ?.
access operators, the chain's execution will either return Option(T).none
on the first encounter of none
or returns the last member as an Option(T).some
: Planned Feature
print root?.a?.b?.c?.last
^topic
if
unwrap. #
The if
statement can be amended to unwrap an optional value using the capture ->
operator:
var opt ?String = 'abc'
if opt -> v:
print v -- Prints 'abc'
^topic
while
unwrap. #
The while
statement can be amended to unwrap an optional value using the capture ->
operator.
The loop exits when none
is encountered:
var iter = dir.walk()
while iter.next() -> entry:
print entry.name
^topic
Type aliases. #
A type alias refers to a different target type. Once declared, the alias and the target type can be used interchangeably.
A type alias is declared using the assignment =
operator after a type
name declaration:
type Vec2:
x float
y float
type Pos2 = Vec2
var pos = Pos2{x: 3, y: 4}
^topic
Distinct types. #
A distinct type creates a new type by copying a target type.
It's declared with type
name declaration followed by the target type specifier:
type Vec2:
x float
y float
type Pos2 Vec2
var pos = Pos2{x: 3, y: 4}
Functions can be declared under the new type's namespace:
use math
type Pos2 Vec2:
func blockDist(o Pos2):
var dx = math.abs(o.x - x)
var dy = math.abs(o.y - y)
return dx + dy
var pos = Pos2{x: 3, y: 4}
var dst = Pos2{x: 4, y: 5}
print pos.blockDist(dst) --> 2
Note that functions declared from the target type do not carry over to the new type.
Unlike a type alias, the new type and the target type can not be used interchangeably since they are different types. However, instances of the new type can be casted to the target type, and vice versa: Planned Feature
type Pos2 Vec2
var a = Pos2{x: 3, y: 4}
var b Vec2 = a as Vec2
^topic
Traits. #
^topicPlanned Feature
Union types. #
^topicPlanned Feature
Generic types. #
Templates are used to specialize type declarations. Since template parameters only exist at compile-time, the #
prefix is used to reference them in the template body:
template(T type)
type MyContainer:
id int
value #T
func get() #T:
return self.value
^topic
Expand type template. #
When the template is invoked with compile-time argument(s), a specialized version of the type is generated.
In this example, String
can be used as an argument since it satisfies the type
parameter constraint:
var a MyContainer(String) = {id: 123, value: 'abc'}
print a.get() -- Prints 'abc'
Note that invoking the template again with the same argument(s) returns the same generated type. In other words, the generated type is always memoized from the input parameters.
^topicControl Flow. #
Cyber provides the common constructs to branch and enter loops.
Branching. #
^topicif
statement. #
Use if
and else
statements to branch the execution of your code depending on conditions. The else
clause can contain a condition which is only evaluated if the previous if or conditional else clause was false
.
var a = 10
if a == 10:
print 'a is 10'
else a == 20:
print 'a is 20'
else:
print 'neither 10 nor 20'
^topic
if
expression. #
An if
expression evaluates a condition in parentheses and returns either the true value or false value.
Unlike the if
statement, the if
expression can not contain else
conditional cases:
var a = 10
var str = if (a == 10) 'red' else 'blue'
^topic
and
/or
#
Use and
and or
logical operators to combine conditions:
var a = 10
if a > 5 and a < 15:
print 'a is between 5 and 15'
if a == 20 or a == 10:
print 'a is 10 or 20'
^topic
Iterations. #
^topicInfinite while
. #
The while
keyword starts an infinite loop which continues to run the code in the block until a break
or return
is reached.
var count = 0
while:
if count > 100:
break
count += 1
^topic
Conditional while
. #
When the while
clause contains a condition, the loop continues to run until the condition is evaluated to false
:
var running = true
var count = 0
while running:
if count > 100:
running = false
count += 1
^topic
for
range. #
for
loops can iterate over a range that starts at an int
(inclusive) to a target int
(exclusive).
The capture operator ->
is used to capture the loop's counter variable:
for 0..4:
performAction()
for 0..100 -> i:
print i -- 0, 1, 2, ... , 99
To decrement the counter instead, use -..
:
for 100-..0 -> i:
print i -- 100, 99, 98, ... , 1
When the range operator ..
is replaced with ..=
, the target int
is inclusive: Planned Feature
for 0..=100 -> i:
print i -- 0, 1, 2, ... , 100
^topic
for
each. #
The for
clause can iterate over any type that implements the Iterable
trait. An Iterable contains an iterator()
method which returns an Iterator
object. The for loop continually invokes the Iterator's next()
method until none
is returned.
Lists can be iterated since they implement the Iterable trait. The capture operator ->
is used to capture the value returned from an iterator's next()
:
var list = [1, 2, 3, 4, 5]
for list -> n:
print n
Maps can be iterated. next()
returns a key and value tuple:
var map = Map{ a: 123, b: 234 }
for map -> entry:
print entry[0]
print entry[1]
Use the destructure syntax to extract the key and value into two separate variables:
for map -> [ key, val ]:
print "key $(key) -> value $(val)"
^topic
for
each with index. #
A counting index can be declared after the each variable. The count starts at 0 for the first value:
var list = [1, 2, 3, 4, 5]
for list -> val, i:
print "index $(i), value $(val)"
^topic
Exit loop. #
Use break
to exit a loop. This loop stops printing once i
reaches 4:
for 0..10 -> i:
if i == 4:
break
print i
^topic
Next iteration. #
Use continue
to skip the rest of the loop and go to the next iteration.
This loop prints 0 through 9 but skips 4:
for 0..10 -> i:
if i == 4:
continue
print i
^topic
switch
matching. #
The switch
statement branches to a case block from a matching case condition. The expression that is matched against comes after switch statement. Multiple cases can be grouped together using a comma separator. An optional else
fallback case is executed when no other cases were matched.
Incomplete: Not all types can be used in the case conditions such as ranges.
var val = 1000
switch val
case 0..100: print 'at or between 0 and 99'
case 100 : print 'val is 100'
case 200:
print 'val is 200'
case 300, 400:
print 'combined case'
else:
print "val is $(val)"
The switch statement requires at least one case
block or an else
block.
When the switch statement begins a new block, the case statements must be indented:
switch val:
case 0: print 'a'
case 1: print 'b'
else: print 'c'
^topic
switch
assignment. #
Although switch
can not be used freely as an expression, it can be assigned to a left variable or destination:
var shu = switch pepper:
case 'bell' => 0
case 'anaheim' => 500
case 'jalapeño' => 2000
case 'serrano' => 10000
When declaring an assignable switch, the cases must have a return value using the syntax case {cond} => {expr}
or else => {expr}
.
switch
break. #
A break
statement exits the current case block and resumes execution after the end of the switch statement: Planned Feature
switch value
case 0..5:
print value
if value == 3:
break case
print value -- Skips second print if `value` is 3.
^topic
Try/Catch. #
The try catch
statement, try else
and try
expressions provide a way to catch a throwing error and resume execution in a different branch. Learn more about Error Handling.
Deferred Execution. #
^topicPlanned Feature
Functions. #
- Static functions.
- Function overloading.
- Lambdas.
- Closures.
- Named parameters.
- Optional parameters.
- Variadic parameters.
- Function calls.
- Generic functions.
In Cyber, there are first-class functions (or function values) and static functions.
Static functions. #
Functions are declared with the func
keyword and must have a name.
use math
func dist(x0 float, y0 float, x1 float, y1 float) float:
var dx = x0-x1
var dy = y0-y1
return math.sqrt(dx^2 + dy^2)
Functions can be invoked with arguments:
print dist(0, 0, 10, 20)
Functions are initially static, but they can be passed around as a lambda or assigned to a variable:
-- Assigning to a local variable.
var bar = dist
func squareDist(dist dynamic, size float) float:
return dist(0.0, 0.0, size, size)
-- Passing `dist` as an argument.
print squareDist(dist, 30.0)
Functions can only return one value. However, the value can be destructured: Planned Feature
use {cos, sin} 'math'
func compute(rad float) [float, float]:
return [ cos(rad), sin(rad) ]
var [ x, y ] = compute(pi)
^topic
Function overloading. #
Functions can be overloaded by their type signature:
func foo() int:
return 2 + 2
func foo(n int) int:
return 10 + n
func foo(n int, m int) int:
return n * m
print foo() --> 4
print foo(2) --> 12
print foo(20, 5) --> 100
^topic
Lambdas. #
Lambdas or function values can be assigned to variables or passed as arguments into other constructs.
When a lambda only returns an expression, it can be declared with a simplified syntax.
-- Passing simple lambda as an argument.
foo(word => toUpper(word))
-- A simple lambda with multiple arguments.
foo((word, prefix) => prefix + toUpper(word))
-- Assigning a simple lambda.
canvas.onUpdate = delta_ms => print delta_ms
Lambdas that need a block of statements can be declared with the func
keyword without a name.
-- Assigning lambda block to a variable.
var add = func (a int, b int) int:
return a + b
-- Passing a lambda block as an argument.
canvas.onUpdate():
..func (delta_ms):
print delta_ms
Passing a lambda block as a call argument is only possible in a call block. Planned Feature See Function calls.
^topicClosures. #
Lambdas can capture local variables from parent blocks. This example shows the lambda f
capturing a
from the main scope: Incomplete, only variables one parent block away can be captured.
var a = 1
var f = func() int:
return a + 2
print f() --> 3
The following lambda expression captures a
from the function add
:
func add():
var a = 123
return b => a + b
var addTo = add()
print addTo(10) --> 133
Like static variables, static functions can not reference local variables outside of their scope:
var a = 1
func foo():
print a --> CompileError: Undeclared variable `a`.
^topic
Named parameters. #
^topicPlanned Feature
Optional parameters. #
^topicPlanned Feature
Variadic parameters. #
^topicPlanned Feature
Function calls. #
The straightforward way to call a function is to use parentheses.
var d = dist(100, 100, 200, 200)
You can call functions with named parameters.
Planned Feature
var d = dist(x0: 10, x1: 20, y0: 30, y1: 40)
^topic
Shorthand syntax. #
Functions can be invoked without parentheses. This only works for calls that take at least one argument. Named arguments are not allowed and nested function calls must use parentheses:
-- Calls the function `dist`.
var d = dist 100, 100, 200, 200
func foo():
return 4
var r = foo -- Returns the function itself as a value.
-- Does not call the function `random`.
r = foo() -- Calls the function `random`.
^topic
Call block syntax. #
The call expression block continues to add arguments from the block's body. If arguments are omitted from the initial call expression they can be added inside using the ..
syntax. Arguments mapped to named parameters have a key value syntax separated by a :
. All other arguments are added into a list and passed as the last argument.
Planned Feature
foo(123):
..func ():
return 123
param3: 123
234
bar()
'hello'
In the example above, the function foo
is called with 4 arguments. The first argument 123
is included in the starting call expression. The second argument is a function value inside the call expression block. The third argument is mapped to the param param3
. Finally, the fourth argument is a list that contains 234
, bar()
, and 'hello'
.
Generic functions. #
^topicPlanned Feature
Modules. #
Modules have their own namespace and contain accessible static symbols. By default, importing another Cyber script returns a module with its declared symbols.
Importing. #
When a use
declaration contains only a single identifier, it creates a local alias to a module using the identifier as the module specifier. Cyber's CLI comes with some builtin modules like math
and test
.
use test
test.eq(123, 123)
use math
print math.cos(0)
The explicit import syntax requires an alias name followed by a module specifier as a raw string:
use m 'math'
print m.random()
When Cyber is embedded into a host application, the module resolver and loader can be overridden using libcyber.
^topicImport file. #
File modules can be imported:
-- Importing a module from the local directory.
use b 'bar.cy'
print b.myFunc()
print b.myVar
^topic
Import URL. #
Modules can be imported over the Internet:
-- Importing a module from a CDN.
use rl 'https://mycdn.com/raylib'
When importing using a URL without a file name, Cyber's CLI will look for a mod.cy
from the path instead.
Import all. #
If the alias name is the wildcard character, all symbols from the module are imported into the using namespace: This feature is experimental and may be removed in a future version.
use * 'math'
print random()
^topic
Main module. #
Only the main module can have top-level statements that aren't static declarations. If an imported module contains top-level statements, they are ignored. In the future, it may result in a compile error instead:
-- main.cy
use a 'foo.cy'
print a.foo
-- foo.cy
use 'bar.cy'
var .foo = 123
print foo -- Statement is ignored.
-- bar.cy
var .bar = 321
print bar -- Statement is ignored.
^topic
Circular imports. #
Circular imports are allowed. In the following example, main.cy
and foo.cy
import each other without any problems.
-- main.cy
use foo 'foo.cy'
func printB():
foo.printC()
foo.printA()
-- foo.cy
use main 'main.cy'
func printA():
main.printB()
func printC():
print 'done'
Static variable declarations from imports can have circular references. Read more about this in Static variables.
^topicDestructure import. #
Modules can also be destructured using the following syntax:
Planned Feature
use { cos, pi } 'math'
print cos(pi)
^topic
Exporting. #
All symbols are exported when the script's module is loaded. However, symbols can be declared with a hidden modifier.
func foo(): -- Exported static function.
print 123
var .bar = 234 -- Exported static variable.
type Thing: -- Exported type.
var a float
^topic
Module URI. #
To get the absolute path of the current module, reference the compile-time constant #modUri
.
This can be used with os.dirName
to get the current module directory.
print #modUri -- Prints '/some/path/foo.cy'
use os
print os.dirName(#modUri) -- Prints '/some/path'
^topic
Symbol visibility. #
All symbols have public visibility. However, when a symbol is declared with a -
prefix, it suggests that it should not be made available to an editor's autocomplete:
-type Foo:
a int
b int
-func add(a int, b int) int:
return a + b
Furthermore, the symbol is excluded when its module is included using use *
.
Symbol alias. #
use
can be used to create an alias to another symbol:
use eng 'lib/engine.cy'
use Vec2 -> eng.Vector2
^topic
Builtin modules. #
Builtin modules are the bare minimum that comes with Cyber. The embeddable library contains these modules and nothing more. They include:
^topicmodule core
#
The core
module contains functions related to Cyber and common utilities. It is automatically imported into each script's namespace.
Sample usage:
-- `print` and `typeof` are available without imports.
print 'hello'
print typeof('my str').id()
func copy(val any) any
Copies a primitive value or creates a shallow copy of an object value.
func dump(val any)
Prints the result of
toCyon
on a value.
func eprint(str any)
Prints a value to the error stream. The host determines how it is printed.
func errorReport() String
func getObjectRc(val any) int
Returns the current reference count of an object.
func is(a any, b any) bool
Returns whether two values refer to the same instance.
func isAlpha(val int) bool
Returns whether a rune is an alphabetic letter.
func isDigit(val int) bool
Returns whether a rune is a digit.
func isNone(val any) bool
Returns whether a boxed value is the
none
case of a genericOption(T)
type. This is temporary and may be removed in a future release.
func must(val any) any
If
val
is an error,panic(val)
is invoked. Otherwise,val
is returned.
func panic(err any) dynamic
Stop execution in the current fiber and starts unwinding the call stack. See Unexpected Errors.
func performGC() Map
Runs the garbage collector once to detect reference cycles and abandoned objects. Returns the statistics of the run in a map value.
func print(str any)
Prints a value. The host determines how it is printed.
func runestr(val int) String
Converts a rune to a string.
^topic
func typeof(val any) metatype
Returns the value's type as a
metatype
object.
type void
#
^topic
type bool
#
^topic
func bool.$call(val any) bool
Converts a value to either
true
orfalse
.
type symbol
#
^topic
type error
#
func sym() symbol
Return the underlying
symbol
.
^topic
func error.$call(val any) error
Create an error from an enum or symbol.
type int
#
func $prefix~() int
func $prefix-() int
func $infix<(o int) bool
func $infix<=(o int) bool
func $infix>(o int) bool
func $infix>=(o int) bool
func $infix+(o int) int
func $infix-(o int) int
func $infix*(o int) int
func $infix/(o int) int
func $infix%(o int) int
func $infix^(o int) int
func $infix&(o int) int
func $infix|(o int) int
func $infix||(o int) int
func $infix<<(o int) int
func $infix>>(o int) int
func fmt(kind symbol) String
Formats the integer using a kind specifier which can be binary
.b
, octal.o
, decimal.d
, hexadecimal.x
, ASCII.c
.
func fmt(kind symbol, config Table) String
opts.pad
provides the ASCII rune that is used for padding with a string length ofconfig.width
.
^topic
func int.$call(val any) int
Converts a value to an 48-bit integer.
type float
#
func $prefix-() float
func $infix<(o float) bool
func $infix<=(o float) bool
func $infix>(o float) bool
func $infix>=(o float) bool
func $infix+(o float) float
func $infix-(o float) float
func $infix*(o float) float
func $infix/(o float) float
func $infix%(o float) float
func $infix^(o float) float
^topic
func float.$call(val any) float
Converts the value to a
float
. Panics if type conversion fails.
type placeholder1
#
^topic
type placeholder2
#
^topic
type placeholder3
#
^topic
type dynamic
#
^topic
type any
#
^topic
type type
#
^topic
type List
#
func $index(idx int) dynamic
func $index(range Range) List
func $setIndex(idx int, val any)
func append(val any)
Appends a value to the end of the list.
func appendAll(list List)
Appends the elements of another list to the end of this list.
func insert(idx int, val any)
Inserts a value at index
idx
.
func iterator() ListIterator
Returns a new iterator over the list elements.
func join(sep String) String
Returns a new string that joins the elements with
separator
.
func len() int
Returns the number of elements in the list.
func remove(idx int)
Removes an element at index
idx
.
func resize(size int)
Resizes the list to
len
elements. If the new size is bigger,none
values are appended to the list. If the new size is smaller, elements at the end of the list are removed.
func sort(lessFn any)
Sorts the list with the given
less
function. If elementa
should be ordered beforeb
, the function should returntrue
otherwisefalse
.
^topic
func List.fill(val any, n int) List
Creates a list with initial capacity of
n
and values set toval
. If the value is an object, it is shallow copiedn
times.
type ListIterator
#
^topic
func next() ?any
type Tuple
#
^topic
func $index(idx int) any
type Table
#
func $initPair(key String, value any)
func $get(name String) dynamic
func $set(name String, value any)
func $index(key any) dynamic
^topic
func $setIndex(key any, value any)
type Map
#
func $initPair(key any, value any)
func $index(key any) any
func $setIndex(key any, val any)
func contains(key any) bool
Returns whether there is a value mapped to
key
.
func get(key any) ?any
Returns value mapped to
key
or returnsnone
.
func remove(key any) bool
Removes the element with the given key
key
.
func size() int
Returns the number of key-value pairs in the map.
^topic
func iterator() MapIterator
Returns a new iterator over the map elements.
type MapIterator
#
^topic
func next() ?any
type String
#
func $infix+(o any) String
Returns a new string that concats this string and
str
.
func concat(o String) String
Returns a new string that concats this string and
str
.
func count() int
Returns the number of runes in the string.
func endsWith(suffix String) bool
Returns whether the string ends with
suffix
.
func find(needle String) ?int
Returns the first byte index of substring
needle
in the string ornone
if not found. SIMD enabled.
func findAnyRune(runes String) ?int
Returns the first byte index of any rune in
runes
ornone
if not found. SIMD enabled.
func findRune(rune int) ?int
Returns the first byte index of a rune
needle
in the string ornone
if not found. SIMD enabled.
func insert(idx int, str String) String
Returns a new string with
str
inserted at byte indexidx
.
func isAscii() bool
Returns whether the string contains all ASCII runes.
func len() int
Returns the byte length of the string. See
count()
to obtain the number of runes.
func less(other String) bool
Returns whether this string is lexicographically before
other
.
func lower() String
Returns this string in lowercase.
func replace(needle String, replacement String) String
Returns a new string with all occurrences of
needle
replaced withreplacement
.
func repeat(n int) String
Returns a new string with this string repeated
n
times.
func seek(idx int) int
Returns the starting byte index for the rune index
idx
.
func sliceAt(idx int) String
Returns the UTF-8 rune starting at byte index
idx
as a string.
func $index(idx int) String
Returns the rune at byte index
idx
. The replacement character (0xFFFD) is returned for an invalid UTF-8 rune.
func $index(range Range) String
Returns a slice into this string from a
Range
withstart
(inclusive) toend
(exclusive) byte indexes.
func split(sep String) List
Returns a list of UTF-8 strings split at occurrences of
sep
.
func startsWith(prefix String) bool
Returns whether the string starts with
prefix
.
func trim(mode symbol, delims String) String
Returns the string with ends trimmed from runes in
delims
.mode
can be .left, .right, or .ends.
func upper() String
Returns this string in uppercase.
^topic
func String.$call(val any) String
Converts a value to a string.
type Array
#
func $infix+(o any) Array
func concat(other Array) Array
Returns a new array that concats this array and
other
.
func decode() String
Calls decode(.utf8)
func decode(encoding symbol) String
Decodes the array based on an
encoding
. Supported encodings:.utf8
. Returns the decoded string or throwserror.Decode
.
func endsWith(suffix Array) bool
Returns whether the array ends with
suffix
.
func find(needle Array) ?int
Returns the first index of
needle
in the array ornone
if not found.
func findAnyByte(bytes Array) ?int
Returns the first index of any
bytes
inarrays
ornone
if not found.
func findByte(byte int) ?int
Returns the first index of
byte
in the array ornone
if not found.
func fmt(kind symbol) String
Formats each byte in the array using a kind specifier which can be binary
.b
, octal.o
, decimal.d
, hexadecimal.x
, ASCII.c
. Each byte is zero padded.
func getByte(idx int) int
Returns the byte value (0-255) at the given index
idx
.
func getInt(idx int, endian symbol) int
Returns the int value of the 6 bytes starting from
idx
with the given endianness (.little or .big).
func getInt32(idx int, endian symbol) int
Returns the int value of the 4 bytes starting from
idx
with the given endianness (.little or .big).
func insert(idx int, arr Array) Array
Returns a new array with
arr
inserted at indexidx
.
func insertByte(idx int, byte int) Array
Returns a new array with
byte
inserted at indexidx
.
func iterator() ArrayIterator
Returns a new iterator over the array bytes.
func len() int
Returns the number of bytes in the array.
func repeat(n int) Array
Returns a new array with this array repeated
n
times.
func replace(needle Array, replacement Array) Array
Returns a new array with all occurrences of
needle
replaced withreplacement
.
func $index(idx int) int
func $index(range Range) Array
Returns a slice into this array from a
Range
withstart
(inclusive) toend
(exclusive) indexes.
func split(sep Array) List
Returns a list of arrays split at occurrences of
sep
.
func startsWith(prefix Array) bool
Returns whether the array starts with
prefix
.
func trim(mode symbol, delims Array) Array
Returns the array with ends trimmed from runes in
delims
.mode
can be .left, .right, or .ends.
^topic
func Array.$call(val any) Array
Converts a string to an byte
Array
.
type ArrayIterator
#
^topic
func next() ?any
type pointer
#
func addr() int
Returns the memory address as an
int
. The value may be negative since it's bitcasted from an unsigned 48-bit integer but it retains the original pointer bits.
func asObject() any
Unsafe. Casts the pointer to a Cyber object. The object is retained before it's returned.
func fromCstr(offset int) Array
Unsafe. Returns an
Array
from a null terminated C string.
func get(offset int, ctype symbol) any
Unsafe. Dereferences the pointer at a byte offset and returns the C value converted to Cyber.
func set(offset int, ctype symbol, val any)
Unsafe. Converts the value to a compatible C value and writes it to a byte offset from this pointer.
func toArray(offset int, len int) Array
Unsafe. Returns an
Array
with a copy of the byte data starting from an offset to the specified length.
^topic
func pointer.$call(val any) pointer
Converts a
int
to apointer
value, or casts to apointer
. This is usually used with FFI.
type Closure
#
^topic
type Lambda
#
^topic
type HostFunc
#
^topic
type ExternFunc
#
^topic
func addr() int
Returns the memory address as an
int
. The value may be negative since it's bitcasted from an unsigned 48-bit integer but it retains the original pointer bits.
type Fiber
#
^topic
func status() symbol
type metatype
#
^topic
func id() int
type Range
#
^topic
type Box
#
^topic
type TccState
#
^topic
module cy
#
The cy
module contains functions related to the Cyber language.
Sample usage:
use cy
print cy.toCyon([1, 2, 3])
func eval(src String) any
Evaluates source code in an isolated VM. If the last statement is an expression, a primitive or a String can be returned.
func parse(src String) Map
Parses Cyber source string into a structured map object. Currently, only metadata about static declarations is made available but this will be extended to include an AST.
func parseCyon(src String) any
Parses a CYON string into a value.
func repl(read_line any)
Starts an isolated REPL session. The callback
read_line(prefix String) String
is responsible for obtaining the input.
^topic
func toCyon(val any) String
Encodes a value to CYON string.
module math
#
The math module contains commonly used math constants and functions.
Sample usage:
use math
var r = 10.0
print(math.pi * r^2)
var e float
Euler's number and the base of natural logarithms; approximately 2.718.
var inf float
Infinity.
var log10e float
Base-10 logarithm of E; approximately 0.434.
var log2e float
Base-2 logarithm of E; approximately 1.443.
var ln10 float
Natural logarithm of 10; approximately 2.303.
var ln2 float
Natural logarithm of 2; approximately 0.693.
var maxSafeInt float
The maximum integer value that can be safely represented as a float. 2^53-1 or 9007199254740991.
var minSafeInt float
The minumum integer value that can be safely represented as a float. -(2^53-1) or -9007199254740991.
var nan float
Not a number. Note that nan == nan. However, if a nan came from an arithmetic operation, the comparison is undefined. Use
isNaN
instead.
var neginf float
Negative infinity.
var pi float
Ratio of a circle's circumference to its diameter; approximately 3.14159.
var sqrt1_2 float
Square root of ½; approximately 0.707.
var sqrt2 float
Square root of 2; approximately 1.414.
func abs(a float) float
Returns the absolute value of x.
func acos(a float) float
Returns the arccosine of x.
func acosh(a float) float
Returns the hyperbolic arccosine of x.
func asin(a float) float
Returns the arcsine of x.
func asinh(a float) float
Returns the hyperbolic arcsine of a number.
func atan(a float) float
Returns the arctangent of x.
func atan2(a float, b float) float
Returns the arctangent of the quotient of its arguments.
func atanh(a float) float
Returns the hyperbolic arctangent of x.
func cbrt(a float) float
Returns the cube root of x.
func ceil(a float) float
Returns the smallest integer greater than or equal to x.
func clz32(a float) float
Returns the number of leading zero bits of the 32-bit integer x.
func cos(a float) float
Returns the cosine of x.
func cosh(a float) float
Returns the hyperbolic cosine of x.
func exp(a float) float
Returns e^x, where x is the argument, and e is Euler's number (2.718…, the base of the natural logarithm).
func expm1(a float) float
Returns subtracting 1 from exp(x).
func floor(a float) float
Returns the largest integer less than or equal to x.
func frac(a float) float
Returns the fractional or decimal part of a float value.
func hypot(a float, b float) float
Returns the square root of the sum of squares of its arguments.
func isInt(a float) bool
Returns true if the float has no fractional part, otherwise false.
func isNaN(a float) bool
Returns whether x is not a number.
func ln(a float) float
Returns the natural logarithm (㏒e; also, ㏑) of x.
func log(a float, b float) float
Returns the logarithm of y with base x.
func log10(a float) float
Returns the base-10 logarithm of x.
func log1p(a float) float
Returns the natural logarithm (㏒e; also ㏑) of 1 + x for the number x.
func log2(a float) float
Returns the base-2 logarithm of x.
func max(a float, b float) float
Returns the largest of two numbers.
func min(a float, b float) float
Returns the smallest of two numbers.
func mul32(a float, b float) float
Returns the result of the 32-bit integer multiplication of x and y. Integer overflow is allowed.
func pow(a float, b float) float
Returns base x to the exponent power y (that is, x^y).
func random() float
Returns a pseudo-random number between 0 and 1.
func round(a float) float
Returns the value of the number x rounded to the nearest integer.
func sign(a float) float
Returns the sign of the x, indicating whether x is positive, negative, or zero.
func sin(a float) float
Returns the sine of x.
func sinh(a float) float
Returns the hyperbolic sine of x.
func sqrt(a float) float
Returns the positive square root of x.
func tan(a float) float
Returns the tangent of x.
func tanh(a float) float
Returns the hyperbolic tangent of x.
^topic
func trunc(a float) float
Returns the integer portion of x, removing any fractional digits.
Std modules. #
Std modules come with Cyber's CLI. They include:
^topicmodule cli
#
The cli
module contains functions related to the command line.
Sample usage:
use cli
cli.repl()
func repl()
Starts an isolated REPL session. Invokes
cy.repl(replReadLine)
.
^topic
func replReadLine(prefix String) String
Default implementation to read a line from the CLI for a REPL.
module os
#
Cyber's os module contains system level functions. It's still undecided as to how much should be included here so it's incomplete. You can still access os and libc functions yourself using Cyber's FFI or embedding API.
Sample usage:
use os
var map = os.getEnvAll()
for map -> [k, v]:
print "$(k) -> $(v)"
var cpu String
The current cpu arch's tag name.
var endian symbol
The current arch's endianness: .little, .big
var stderr File
Standard error file descriptor.
var stdin File
Standard input file descriptor.
var stdout File
Standard output file descriptor.
var system String
The current operating system's tag name.
var vecBitSize int
Default SIMD vector bit size.
func access(path String, mode symbol)
Attempts to access a file at the given
path
with the.read
,.write
, or.readWrite
mode. Throws an error if unsuccessful.
func args() List
Returns the command line arguments in a
List
. Each argument is converted to aString
.
func cacheUrl(url String) String
Returns the path of a locally cached file of
url
. If no such file exists locally, it's fetched fromurl
.
func copyFile(srcPath String, dstPath String)
Copies a file to a destination path.
func createDir(path String)
Creates the directory at
path
. Returnstrue
if successful.
func createFile(path String, truncate bool) File
Creates and opens the file at
path
. Iftruncate
is true, an existing file will be truncated.
func cstr(s any) pointer
Returns a null terminated C string.
func cwd() String
Returns the current working directory.
func dirName(path String) ?String
Returns the given path with its last component removed.
func execCmd(args List) Map
Runs a shell command and returns the stdout/stderr.
func exePath() String
Returns the current executable's path.
func exit(status int)
Exits the program with a status code.
func fetchUrl(url String) Array
Fetches the contents at
url
using the HTTP GET request method.
func free(ptr pointer)
Frees the memory located at
ptr
.
func getEnv(key String) ?String
Returns an environment variable by key.
func getEnvAll() Map
Returns all environment variables as a
Map
.
func malloc(size int) pointer
Allocates
size
bytes of memory and returns a pointer.
func milliTime() float
Return the calendar timestamp, in milliseconds, relative to UTC 1970-01-01. For an high resolution timestamp, use
now()
.
func newFFI() FFI
Returns a new FFI context for declaring C mappings and binding a dynamic library.
func now() float
Returns the current time (in high resolution seconds) since an arbitrary point in time.
func openDir(path String) Dir
Invokes
openDir(path, false)
.
func openDir(path String, iterable bool) Dir
Opens a directory at the given
path
.iterable
indicates that the directory's entries can be iterated.
func openFile(path String, mode symbol) File
Opens a file at the given
path
with the.read
,.write
, or.readWrite
mode.
func parseArgs(options List) Table
Given expected
ArgOption
s, returns aTable
of the options and arest
entry which contains the non-option arguments.
func readAll() String
Reads stdin to the EOF as a UTF-8 string. To return the bytes instead, use
stdin.readAll()
.
func readFile(path String) String
Reads the file contents from
path
as a UTF-8 string. To return the bytes instead, useFile.readAll()
.
func readLine() String
Reads stdin until a new line as a
String
. This is intended to read user input from the command line. For bulk reads from stdin, usestdin
.
func realPath(path String) String
Returns the absolute path of the given path.
func removeDir(path String)
Removes an empty directory at
path
. Returnstrue
if successful.
func removeFile(path String)
Removes the file at
path
. Returnstrue
if successful.
func setEnv(key String, val String)
Sets an environment variable by key.
func sleep(ms float)
Pauses the current thread for given milliseconds.
func unsetEnv(key String)
Removes an environment variable by key.
^topic
func writeFile(path String, contents any)
Writes
contents
as a string or bytes to a file.
type File
#
func close()
Closes the file handle. File ops invoked afterwards will return
error.Closed
.
func iterator() any
func next() any
func read(n int) Array
Reads at most
n
bytes as anArray
.n
must be at least 1. A result with length 0 indicates the end of file was reached.
func readAll() Array
Reads to the end of the file and returns the content as an
Array
.
func seek(n int)
Seeks the read/write position to
pos
bytes from the start. Negativepos
is invalid.
func seekFromCur(n int)
Seeks the read/write position by
pos
bytes from the current position.
func seekFromEnd(n int)
Seeks the read/write position by
pos
bytes from the end. Positivepos
is invalid.
func stat() Map
Returns info about the file as a
Map
.
func streamLines() File
Equivalent to
streamLines(4096)
.
func streamLines(bufSize int) File
Returns an iterable that streams lines ending in
\n
,\r
,\r\n
, or theEOF
. The lines returned include the new line character(s). A buffer size ofbufSize
bytes is allocated for reading. If\r
is found at the end of the read buffer, the line is returned instead of waiting to see if the next read has a connecting\n
.
^topic
func write(val any) int
Writes a
String
orArray
at the current file position. The number of bytes written is returned.
type Dir
#
func iterator() DirIterator
Returns a new iterator over the directory entries. If this directory was not opened with the iterable flag,
error.NotAllowed
is returned instead.
func stat() Map
Returns info about the file as a
Map
.
^topic
func walk() DirIterator
Returns a new iterator over the directory recursive entries. If this directory was not opened with the iterable flag,
error.NotAllowed
is returned instead.
type DirIterator
#
^topic
func next() ?Map
type FFI
#
func bindCallback(fn any, params List, ret symbol) ExternFunc
Creates an
ExternFunc
that contains a C function pointer with the given signature. The extern function is a wrapper that calls the provided user function. Once created, the extern function is retained and managed by the FFI context.
func bindLib(path ?String) any
Calls
bindLib(path, [:])
.
func bindLib(path ?String, config Table) any
Creates a handle to a dynamic library and functions declared from
cfunc
. By default, an anonymous object is returned with the C-functions binded as the object's methods. Ifconfig
containsgen_table: true
, aTable
is returned instead with C-functions binded as function values.
func bindObjPtr(obj any) pointer
Returns a Cyber object's pointer. Operations on the pointer is unsafe, but it can be useful when passing it to C as an opaque pointer. The object is also retained and managed by the FFI context.
func cbind(mt metatype, fields List)
Binds a Cyber type to a C struct.
func cfunc(name String, params List, ret any)
Declares a C function which will get binded to the library handle created from
bindLib
.
func new(ctype symbol) pointer
Allocates memory for a C struct or primitive with the given C type specifier. A
pointer
to the allocated memory is returned. Eventually this will return acpointer
instead which will be more idiomatic to use.
^topic
func unbindObjPtr(obj any)
Releases the object from the FFI context. External code should no longer use the object's pointer since it's not guaranteed to exist or point to the correct object.
type CArray
#
^topic
type CDimArray
#
^topic
Map DirEntry
#
key | summary |
---|---|
'name' -> Array | The name of the file or directory. |
'type' -> #file | #dir | #unknown | The type of the entry. |
Map DirWalkEntry
#
key | summary |
---|---|
'name' -> Array | The name of the file or directory. |
'path' -> Array | The path of the file or directory relative to the walker's root directory. |
'type' -> #file | #dir | #unknown | The type of the entry. |
Table ArgOption
#
key | summary |
---|---|
'name' -> String | The name of the option to match excluding the hyphen prefix. eg. -path |
'type' -> metatype(String | float | boolean) | Parse as given value type. |
'default' -> any | Optional: Default value if option is missing. none is used if this is not provided. |
module test
#
The test
module contains utilities for testing.
Sample usage:
use t 'test'
var a = 123 + 321
t.eq(a, 444)
func assert(pred bool)
Panics if
pred
isfalse
.
func eq(a any, b any) bool
Returns whether two values are equal. Panics with
error.AssertError
if types or values do not match up.
func eqList(a any, b any) bool
Returns
true
if two lists have the same size and the elements are equal as ifeq
was called on those corresponding elements.
func eqNear(a any, b any) bool
Returns
true
if two numbers are near each other within epsilon 1e-5.
func fail()
func fail(msg String)
^topic
func throws(fn any, err error)
Asserts that an error was thrown when invoking a function.
FFI. #
Cyber supports binding to an existing C ABI compatible library at runtime.
This allows you to call into dynamic libraries created in C or other languages.
Cyber uses libtcc
to JIT compile the bindings so function calls are fast.
The example shown below can be found in Examples.
FFI context. #
An FFI context contains declarations that map C to Cyber. Afterwards, it allows you to bind to a dynamic library or create interoperable objects. To create a new FFI
context:
use os
var ffi = os.newFFI()
^topic
Declare functions. #
Functions from a library are first declared using cfunc
which accepts C types in the form of symbols. In a future update they will accept C syntax instead.
ffi.cfunc('add', [.int, .int], .int)
The first argument refers to the symbol's name in the dynamic library. The second argument contains the function's parameter types and finally the last argument is the function's return type.
The example above maps to this C function:
int add(int a, int b) {
return a + b;
}
^topic
Bind library. #
bindLib
accepts the path to the library and returns a object which can be used to invoke the functions declared from cfunc
:
let lib = ffi.bindLib('./mylib.so')
lib.add(123, 321)
Note that let
is used to allow lib
to be used dynamically since the type is unknown at compile-time.
Search path. #
If the path argument to bindLib
is just a filename, the search steps for the library is specific to the operating system. Provide an absolute (eg. '/foo/mylib.so') or relative (eg. './mylib.so') path to load from a direct location instead. When the path argument is none
, it loads the currently running executable as a library allowing you to bind exported functions from the Cyber CLI or your own application/runtime.
Configuration. #
By default bindLib
returns an anonymous object with the binded C-functions as methods. This is convenient for invoking functions using the method call syntax. If a config is passed into bindLib
as the second argument, gen_table: true
makes bindLib
return a table instead with the binded C-functions as Cyber functions.
Finalizer. #
The resulting object of bindLib
holds a reference to an internal TCCState which owns the loaded JIT code.
Once the object is released by ARC, the TCCState is also released which removes the JIT code from memory.
Mappings. #
When using cfunc
or cbind
declarations, symbols are used to represent default type mappings from Cyber to C and back:
Incomplete: This is not the final API for dynamically loading and interfacing with C libraries. The plan is to parse a subset of C headers to bind to Cyber types and functions.
Binding | Cyber | C |
---|---|---|
.bool | bool | bool |
.char | int | int8_t, signed char |
.uchar | int | uint8_t, unsigned char |
.short | int | int16_t, short |
.ushort | int | uint16_t, unsigned short |
.int | int | int32_t, int |
.uint | int | uint32_t, unsigned int |
.long | int | int64_t, long long |
.ulong | int | uint64_t, unsigned long long |
.usize | int | size_t, uintptr_t |
.float | float | float |
.double | float | double |
(1) .charPtr | pointer | char* |
.voidPtr | pointer | void* |
(2) type {S} | type {S} | struct |
- Use
os.cstr()
andpointer.fromCstr()
to convert between a Cyber string and a null terminated C string. - The mapping from a Cyber object type
S
and the C-struct can be declared withcbind
.
Bind to Cyber type. #
cbind
is used to bind a C struct to a Cyber object type. Once declared, the Cyber type can be used as a binding type in function declarations:
use os
type MyObject:
a float
b pointer
c bool
ffi.cbind(MyObject, [.float, .voidPtr, .bool])
ffi.cfunc('foo', [MyObject], MyObject)
let lib = ffi.bindLib('./mylib.so')
var res = lib.foo(MyObject{a: 123.0, b: os.cstr('foo'), c: true})
The example above maps to these C declarations in mylib.so
:
typedef struct MyObject {
double a;
char* b;
bool c;
} MyObject;
MyObject foo(MyObject o) {
// Do something.
}
cbind
also generates ptrTo[Type]
as a helper function to dereference an opaque ptr to a new Cyber object:
ffi.cfunc('foo', [MyObject], .voidPtr)
let lib = ffi.bindLib('./mylib.so')
var ptr = lib.foo(MyObject{a: 123, b: os.cstr('foo'), c: true})
var res = lib.ptrToMyObject(ptr)
^topic
Pointers. #
A pointer
is used to read or write to an exact memory address. This is typically used for FFI to manually map Cyber types to C, and back. See type pointer
.
A new pointer can be created with the builtin pointer
.
var ptr = pointer(0xDEADBEEF)
print ptr.value() --'3735928559'
^topic
cbindgen.cy #
cbindgen.cy is a Cyber script that automatically generates bindings given a C header file. Some example bindings that were generated include: Raylib and LLVM.
^topicError Handling. #
Cyber provides a throw/catch mechanism to handle expected errors. For unexpected errors, panics can be used as a fail-fast mechanism to abort the currently running fiber.
Error value. #
^topicerror
literal. #
An error
value contains a symbol
. They can be created without a declaration using the error literal:
var err = error.Oops
Use sym()
to obtain the underlying symbol:
print err.sym() -- Prints ".Oops"
Since error
is a primitive value, it can be compared using the ==
operator.
if err == error.Oops:
handleOops()
-- Alternatively.
if err.sym() == .Oops:
handleOops()
^topic
error
payload. #
An payload value can be attached when throwing an error value. Planned Feature
^topicerror
set type. #
Error set types enumerate error values that belong to the same group of errors: Planned Feature
type MyError error:
case boom
case badArgument
case nameTooLong
var err = MyError.nameTooLong
^topic
Throwing errors. #
Use the throw
keyword to throw errors.
A thrown error continues to bubble up the call stack until it is caught by a try
block or try
expression.
func fail():
throw error.Oops -- Throws an error with the symbol `#Oops`
func fail2():
throw 123 -- panic: Can only throw an `error` value.
throw
can also be used as an expression.
func fail():
var a = false or throw error.False
^topic
Catching errors. #
^topictry
block. #
The try
block catches thrown errors and resumes execution in a followup catch
block:
try:
funcThatCanFail()
catch err:
print err -- 'error.Failed'
^topic
caught
variable. #
The contextual caught
variable is used to reference the caught error: Planned Feature
try:
funcThatCanFail()
catch:
print caught -- 'error.Failed'
^topic
catch
matching. #
An inner catch
block contains a matching clause: Planned Feature
try:
funcThatCanFail()
catch error.BadDay:
eatSnack()
catch:
print caught
Error sets can be matched: Planned Feature
try:
funcThatCanFail()
catch MyError.Boom:
print 'Kaboom!'
catch:
print caught
^topic
try
expression. #
The try
expression either returns a non-error result or the default value from the catch
clause:
var res = try funcThatCanFail() catch 123
print res -- '123'
Since errors bubble up automatically, any errors thrown from sub-expressions are also caught:
var res = try happyFunc(funcThatCanFail()) catch 123
print res -- '123'
^topic
Value or error. #
When the catch
clause is omitted, the try
expression will return either the value or the error:
var res = try funcThatCanFail()
if res == error.Failed:
print 'Result is an error.'
^topic
Semantic checks. #
^topicthrows specifier. #
The throws specifier !
indicates that a function contains a throwing expression that was not caught with try catch
.
The specifier is attached to the function return type as a prefix:
func foo() !void:
throw error.Failure
This declaration indicates the function can either return an int
type or throw an error:
func result(cond bool) !int:
if cond:
return 123
else:
throw error.Failure
^topic
throws check. #
The compiler requires a throws specifier if the function contains an uncaught throwing expression: Planned Feature
func foo(a int) int:
if a == 10:
throw error.Failure --> CompileError.
else:
return a * 2
--> CompileError. Uncaught throwing expression.
--> `foo` requires the `!` throws specifier or
--> the expression must be caught with `try`.
^topic
Stack trace. #
When an uncaught error bubbles up to the top, its stack trace from the throw
callsite is dumped to the console. The builtin errorTrace()
and errorReport()
are used to obtain the stack trace info.
try:
funcThatCanFail()
catch:
-- Prints the stack trace summary of the caught error.
print errorReport()
-- Provides structured info about the stack trace.
var info = errorTrace()
print info.frames.len()
^topic
Unexpected errors. #
An unexpected error is an error that is not meant to be handled at runtime.
^topicPanics. #
The builtin panic
is used as a fail-fast mechanism to quickly exit the current fiber with an error payload:
func kaboom():
panic(error.danger)
kaboom() -- Script ends and prints the stack trace.
Panics can not be caught using try catch
. Once panic
is invoked, the current fiber stops execution and begins to unwind its call stack. Once the error is propagated to the root, the fiber ends and transitions to a panic state. If the main fiber ends this way, the VM begins to shutdown. Otherwise, execution resumes on the next fiber which allows recovery from a panic.
Concurrency. #
Cyber supports fibers as a concurrency mechanism. There are plans to support preemptive concurrency with async/await as well as multithreading.
Fibers. #
A fiber represents a separate execution context as a first-class value. It contains it's own call stack and program counter. Fibers by themselves do not enable parallelism.
^topicCreating fibers. #
The coinit
keyword creates and returns a new fiber using a function as the entry point:
var count = 0
var foo = func ():
count += 1
coyield
count += 1
var fiber = coinit(foo)
print count -- '0'
coresume fiber
print count -- '1'
coresume fiber
print count -- '2'
A fiber does not start execution until coresume
is invoked on it.
coyield
pauses the current fiber and execution is returned to the previous fiber that invoked coresume
.
Passing arguments. #
Arguments after the callee are passed into the entry function:
var count = 0
var increment = func (inc):
count += inc
var fiber = coinit(increment, 5)
coresume fiber
print count -- '5'
When the fiber is created, the arguments are saved inside the fiber's stack. Once the first coresume
is invoked, the entry function is invoked with the saved arguments.
Reset state. #
To reset a fiber to its initial state, invoke reset()
. Planned Feature
When reset, the existing stack is unwinded, the program counter returns to the starting point, and the state is set to .init
:
func fib(n int) int:
coyield n
if n < 2:
return n
return fib(n - 1) + fib(n - 2)
var task = coinit(fib, 10)
-- Progress the fiber...
print(coresume task) -- Prints "10"
print(coresume task) -- Prints "9"
print(coresume task) -- Prints "8"
-- Reset back to the start with the `.init` state.
fiber.reset()
print(coresume task) -- Prints "10"
^topic
Rebinding arguments. #
Arguments attached to the fiber can be rebinded with a different set of values. Planned Feature This allows fiber reuse, instead of creating a new fiber:
var task = coinit(fib, 10)
-- Run task to completion.
var res = 0
while fiber.status() != .done:
res = coresume fiber
print res
fiber.reset()
fiber.bindArgs(20)
-- Run task again with the new argument...
^topic
Fiber block. #
A fiber block is used to construct a fiber without an entry function. Planned Feature The counting example can be rewritten to:
var count = 0
var fiber = coinit:
count += 1 -- `count is captured`
coyield
count += 1
print count -- '0'
coresume fiber
print count -- '1'
coresume fiber
print count -- '2'
Referencing parent variables from the fiber block automatically captures them just like a function closure.
^topicPause and resume. #
coyield
can be used anywhere in a fiber's call stack to pause execution and return to the previous fiber.
func foo():
print 'foo'
bar()
func bar():
-- Nested coyield in call stack.
coyield
print 'bar'
var fiber = coinit(foo)
coresume fiber
coresume
also returns the resulting value.
func foo():
return 123
var fiber = coinit(foo)
print(coresume fiber) -- '123'
coyield
can return a value back to coresume
. Planned Feature
Fiber state. #
Use Fiber.status()
to get the current state of the fiber.
func foo():
coyield
print 'done'
var fiber = coinit(foo)
print fiber.status() -- '.paused'
coresume fiber
print fiber.status() -- '.paused'
coresume fiber
print fiber.status() -- '.done'
The main execution context is a fiber as well. Once the main fiber has finished, the VM is done and control is returned to the host.
^topicGas mileage. #
^topicPlanned Feature
Async. #
^topicPlanned Feature
Multi-thread. #
^topicPlanned Feature
Dynamic Typing. #
Dynamic typing is supported with a less restrictive syntax. This can reduce the amount of friction when writing code, but it can also result in more runtime errors.
In Cyber, the let
keyword is used exclusively for dynamic declarations.
Dynamic variables. #
Variables declared with let
are implicitly given the dynamic
type:
let a = 123
Typically a dynamic variable defers type checking to runtime, but if the compiler determines that an operation will always fail at runtime, a compile error is reported instead:
let a = '100'
print a / 2
--> CompileError: Can not find the symbol `$infix/` in `String`
When a
is assigned a different type of value, its recent type is updated so the compiler can continue to surface errors ahead of time:
a = [1, 2, 3]
print a / 2
--> CompileError: Can not find the symbol `$infix/` in `List`
^topic
Runtime type checking. #
If the type of a dynamic variable can not be determined at compile-time, type checking is deferred to runtime.
In this example, the type for a
is unknown after assigning the return of a dynamic call to erase
.
Any operation on a
would defer type checking to runtime:
let a = erase(123)
print a(1, 2, 3)
--> panic: Expected a function.
If a dynamic variable's recent type differs between two branches of execution, the type is considered unknown after the branches are merged. Any operations on the variable afterwards will defer type checking to runtime:
let a = 123
if a > 20:
a = 'hello'
-- Branches are merged. `a` has an unknown type.
print a(1, 2, 3)
--> panic: Expected a function.
^topic
Dynamic functions. #
Functions declared with let
do not allow typed parameters or a return specifier.
All parameters are implicitly given the dynamic
type.
The return specifier is also implicitly !dynamic
which indicates that the function can throw an error. This is only relevant when typed code calls a dynamic function:
let foo(a, b, c):
return a + b() + a[c]
The function foo
is a static function. It can't be reassigned like a variable after its declaration.
However, function values (lambdas) assigned to variables allow reassignment. Lambdas can also capture variables from the parent scope:
let count = 123
let f = (a, b):
return a + b(10) + count
-- Reassign `f`.
f = (a, b):
return count * 2 - b(a)
Lambdas that simply return an expression can be written as:
f = (a, b) => a + b(10)
^topic
Dynamic tables. #
The builtin Table
type is used to create dynamic objects.
Tables are initialized with the record literal:
let a = {}
a.name = 'Nova'
print a.name --> Nova
Read more about how to use Tables.
^topicCustom tables. #
Custom tables allow declaring fields and methods.
let Counter{ count }:
let inc():
count += 1
let c = Counter{ count: 0 }
c.inc()
print c.count --> 1
Fields are declared inside the braces and separated with commas. Unlike typed declarations, the fields declared only serve as a subset constraint. Additional fields can still be initialized and used.
Tables can be declared without any methods:
let Vec3{x, y, z}
let v = Vec3{x: 1, y: 2, z: 3}
^topic
Metaprogramming. #
Operator overloading. #
All operators are implemented as object methods.
Incomplete: Not all operators have transitioned to the method paradigm.
To overload an operator for an object type, declare $prefix
, $infix
, $postfix
methods. See the available builtin operators. Since operator names aren't allowed as standard identifiers, they are contained in a string literal.
type Vec2:
x float
y float
func '$infix+'(o Vec2) Vec2:
return Vec2{
x: x + o.x,
y: y + o.y,
}
func '$prefix-'() Vec2:
return Vec2{x: -x, y: -y}
var a = Vec2{x: 1, y: 2}
var b = a + Vec2{x: 3, y: 4}
var c = -a
Some special operators have their own name. This example overloads the index
operator and the set index
operator:
type MyCollection:
arr List
func $index(idx):
return arr[idx * 2]
func $setIndex(idx, val):
arr[idx * 2] = val
var a = MyCollection{arr: [1, 2, 3, 4]}
print a[1] -- Prints `3`
^topic
Builtin operators. #
A list of all supported operators:
Operator | Name |
---|---|
Bitwise not | $prefix~ |
Minus | $prefix- |
Greater | $infix> |
Greater equal | $infix>= |
Less | $infix< |
Less equal | $infix<= |
Add | $infix+ |
Subtract | $infix- |
Multiply | $infix* |
Divide | $infix/ |
Modulus | $infix% |
Power | $infix^ |
Bitwise and | $infix& |
Bitwise or | $infix| |
Bitwise xor | $infix|| |
Bitwise left shift | $infix<< |
Bitwise right shift | $infix>> |
Index | $index |
Set index | $setIndex |
Slice | $slice |
Custom operators. #
^topicPlanned Feature
Magic functions. #
^topicCall module. #
Declare a $call
function to allow invoking a module as a function.
-- Object types are also modules.
type Vec2:
x float
y float
func Vec2.$call(x float, y float) Vec2:
return Vec2{x: x, y: y}
var v = Vec2(1, 2)
^topic
$initRecord
method. #
^topicPlanned Feature
$initPair
method. #
The $initPair
method overrides the record initializer.
After an instance of the type is created from its default record initializer, this method is invoked for each key-value pair in the record literal:
type MyMap:
func $initPair(key any, value any) void:
print "$(key): $(value)"
var m = MyMap{ a: 123, b: 234 }
--> a: 123
--> b: 234
$initPair
is only allowed if the type has a default record initializer or $initRecord
is declared.
$get
method. #
The $get
method allows overriding field accesses for undeclared fields:
type Foo:
func $get(name String):
return name.len()
var f = Foo{}
print f.abc --> 3
print f.hello --> 5
^topic
$set
method. #
The $set
method allows overriding field assignments for undeclared fields:
type Foo:
func $set(name String, value any):
print "setting $(name) $(value)"
var f = Foo{}
f.abc = 123 --> setting abc 123
^topic
Missing method. #
Declare a $missing
method as a fallback when a method was not found in an instance.
Planned Feature
type A:
func $missing(args...):
return args.len
var a = A{}
print a.foo() -- Output: '0'
print a.bar(1, 2) -- Output: '2'
^topic
Reflection. #
A type metatype
object references an internal type. Use the typeof
builtin to get the metatype
of a value.
var val = 123
print typeof(val) -- 'type: float'
-- Referencing a type as a value also returns its `metatype`.
print bool -- 'type: bool'
^topic
Directives. #
Directives start with #
and are used as modifiers.
^topic
#host
Modifier to bind a function, variable, or type to the host. See libcyber.
Generics. #
Generics enables parametric polymorphism for types and functions. Compile-time arguments are passed to templates to generate specialized code. This facilitates developing container types and algorithms that operate on different types.
See Custom Types / Generic types and Functions / Generic functions.
^topicMacros. #
^topicPlanned Feature
Compile-time execution. #
^topicPlanned Feature
Builtin types. #
Builtin types are used internally by the compiler to define it's own primitive types such as bool
, int
, and float
.
type bool_t
type int64_t
^topic
type float64_t
Builtin functions. #
^topic
func genLabel(name String)
Emits a label during codegen for debugging.
Builtin constants. #
^topic
var modUri String
Evaluates to the module's URI as a string. See Module URI.
Runtime execution. #
cy.eval
evaluates source code in an isolated VM.
If the last statement is an expression, a primitive or String can be returned to the caller:
use cy
var res = cy.eval('1 + 2')
print res --> 3
^topic
libcyber. #
libcyber
allows embedding the Cyber compiler and VM into applications. Cyber's core types and the CLI app were built using the library.
The API is defined in the C header file. The examples shown below can be found in the repository under c-embedded. C is used as the host language, but it can be easily translated to C++ or any C-ABI compatible language.
Types and constants from the C-API begin with CL
and functions begin with cl
.
Getting started. #
^topicCreate VM. #
Most operations are tied to a VM handle. To create a new VM instance, call clCreate
:
#include "cyber.h"
int main() {
CLVM* vm = clCreate();
// ...
clDestroy(vm);
return 0;
}
^topic
Override print
. #
The builtin print
function does nothing by default, so it needs to be overrided to print to stdout for example:
void printer(CLVM* vm, CLStr str) {
printf("Invoked printer: %.*s\n", (int)str.len, str.buf);
}
int main() {
// ...
clSetPrinter(vm, printer);
// ...
}
Note that print
invokes the printer twice, once for the value's string and another for the new line character.
Eval script. #
clEval
compiles and evaluates a script:
CLStr src = STR(
"var a = 1\n"
"print(a + 2)\n"
);
CLValue val;
int res = clEval(vm, src, &val);
if (res == CS_SUCCESS) {
printf("Success!\n");
clRelease(vm, val);
} else {
const char* report = clNewLastErrorReport(vm);
printf("%s\n", report);
clFreeStrZ(report);
}
If a value is returned from the main block of the script, it's saved to the result value argument.
Memory is managed by ARC so a value that points to a heap object requires a clRelease
when it's no longer needed.
clEval
returns a result code that indicates whether it was successful.
Module Loader. #
A module loader describes how a module is loaded when use
import statement is encountered during script execution.
Only one module loader can be active and is set using clSetModuleLoader
:
bool modLoader(CLVM* vm, CLStr spec, CLModuleLoaderResult* out) {
if (strncmp("my_mod", spec.buf, spec.len) == 0) {
out->src =
"#host func add(a float, b float) float\n"
"#host var .MyConstant float\n"
"#host var .MyList List\n"
"\n"
"#host\n"
"type MyCollection:\n"
" #host func asList() any"
"\n"
"#host func MyCollection.new(a, b) MyCollection\n";
out->funcLoader = funcLoader;
out->varLoader = varLoader;
out->typeLoader = typeLoader;
return true;
} else {
// Fallback to the default module loader to load `core`.
return clDefaultModuleLoader(vm, spec, out);
}
}
int main() {
//...
clSetModuleLoader(vm, modLoader);
//...
}
The above example checks whether "my_mod" was imported and returns it's source code. Additional loaders are returned to load the functions, variables, and types from the source code.
^topicDefault module loader. #
Since only one module loader can be set to the VM instance, a custom loader is required to handle the "core" import which contains all of the core types and functions in Cyber. This can simply be delegated to clDefaultModuleLoader
.
Function loader. #
A function loader describes how to load a #host
function when it's encountered by the compiler.
The loader can bind functions and type methods:
struct { char* n; CLFuncFn fn; } funcs[] = {
{"add", add},
{"asList", myCollectionAsList},
{"MyCollection.new", myCollectionNew},
};
bool funcLoader(CLVM* vm, CLFuncInfo info, CLFuncResult* out) {
// Check that the name matches before setting the function pointer.
if (strncmp(funcs[info.idx].n, info.name.buf, info.name.len) == 0) {
out->ptr = funcs[info.idx].fn;
return true;
} else {
return false;
}
}
This example uses the CLFuncInfo.idx
of a #host function to index into an array and return a Host function pointer. The name is also compared to ensure it's binding to the correct pointer.
This is an efficient way to map Cyber functions to host functions. A different implementation might use a hash table to map the name of the function to it's pointer.
^topicVariable loader. #
A variable loader describes how to load a #host
variable when it's encountered by the compiler:
// C has limited static initializers (and objects require a vm instance) so initialize them in `main`.
typedef struct { char* n; CLValue v; } NameValue;
NameValue vars[2];
bool varLoader(CLVM* vm, CLVarInfo info, CLValue* out) {
// Check that the name matches before setting the value.
if (strncmp(vars[info.idx].n, info.name.buf, info.name.len) == 0) {
// Objects are consumed by the module.
*out = vars[info.idx].v;
return true;
} else {
return false;
}
}
int main() {
// ...
// Initialize var array for loader.
vars[0] = (NameValue){".MyConstant", clFloat(1.23)};
CLValue myInt = clInteger(123);
vars[1] = (NameValue){".MyList", clNewList(vm, &myInt, 1)};
// ...
}
This example uses the same technique as the function loader, but it can be much simpler. It doesn't matter how the mapping is done as long as the variable loader returns a CLValue
.
Type loader. #
A type loader describes how to load a #host
type when it's encountered by the compiler:
CLTypeId myCollectionId;
bool typeLoader(CLVM* vm, CLTypeInfo info, CLTypeResult* out) {
if (strncmp("MyCollection", info.name.buf, info.name.len) == 0) {
out->type = CS_TYPE_OBJECT;
out->data.object.outTypeId = &myCollectionId;
out->data.object.getChildren = myCollectionGetChildren;
out->data.object.finalizer = myCollectionFinalizer;
return true;
} else {
return false;
}
}
When binding to the "MyCollection" type, it's typeId is saved to outTypeId
. This id is then used to create new instances of this type. See Host types.
Host functions. #
A host function requires a specific function signature:
CLValue add(CLVM* vm, const CLValue* args, uint8_t nargs) {
double res = clAsFloat(args[0]) + clAsFloat(args[1]);
return clFloat(res);
}
A host function should always return a CLValue
. clNone()
can be returned if the function does not intend to return any value.
Host types. #
A host type are types that are opaque to Cyber scripts but still behave like an object. They can have type functions and methods.
Only the host application can directly create new instances of them, so usually a function is binded to expose a constructor to the user script:
// Binding a C struct with it's own children and finalizer.
// This struct retains 2 VM values and has 2 arbitrary data values unrelated to the VM.
typedef struct MyCollection {
CLValue val1;
CLValue val2;
int a;
double b;
} MyCollection;
// Implement the `new` function in MyCollection.
CLValue myCollectionNew(CLVM* vm, const CLValue* args, uint8_t nargs) {
// Instantiate our object.
CLValue new = clNewHostObject(vm, myCollectionId, sizeof(MyCollection));
MyCollection* my = (MyCollection*)clAsHostObject(new);
// Assign the constructor args passed in and retain them since the new object now references them.
clRetain(vm, args[0]);
my->val1 = args[0];
clRetain(vm, args[1]);
my->val2 = args[1];
// Assign non VM values.
my->a = 123;
my->b = 9999.999;
return new;
}
clNewHostObject
takes the type id (returned from the Type loader) and size (in bytes) and returns a new heap object. Note that the size is allowed to vary. Different instances of the same type can occupy different amounts of memory.
getChildren
#
Since MyCollection
contains CLValue
children, the Type loader requires a getChildren
callback so that memory management can reach them:
CLValueSlice myCollectionGetChildren(CLVM* vm, void* obj) {
MyCollection* my = (MyCollection*)obj;
return (CLValueSlice){ .ptr = &my->val1, .len = 2 };
}
^topic
finalizer
#
A type finalizer is optional since the memory and children of an instance will be freed automatically by ARC. However, it can be useful to perform additional cleanup tasks for instances that contain external resources.
void myCollectionFinalizer(CLVM* vm, void* obj) {
printf("MyCollection finalizer was called.\n");
}
^topic
Memory. #
Cyber provides memory safety by default.
ARC. #
Cyber uses ARC or automatic reference counting to manage memory. ARC is deterministic and has less overhead compared to a tracing garbage collector. Reference counting distributes memory management, which reduces GC pauses and makes ARC suitable for realtime applications. One common issue in ARC implementations is reference cycles which Cyber addresses with Weak References and it's very own Cycle Detection.
^topicReference counting. #
In Cyber, there are primitive and object values. Primitives don't need any memory management, since they are copied by value and no heap allocation is required (with the exception of primitives being captured by a closure.
Objects are managed by ARC. Each object has its own reference counter. Upon creating a new object, it receives a reference count of 1. When the object is copied, it's retained and the reference count increments by 1. When an object value is removed from it's parent or is no longer reachable in the current stack frame, it is released and the reference count decrements by 1.
Once the reference count reaches 0 the object begins its destruction procedure. First, child references are released thereby decrementing their reference counts by 1. If the object is a host object, it will invoke its finalizer
function. Afterwards, the object is freed from memory.
Optimizations. #
The compiler can reduce the number of retain/release ops since it can infer value types even though they are dynamically typed to the user. Arguments passed to functions are only retained depending on the analysis from the callsite.
^topicClosures. #
When primitive variables are captured by a closure, they are boxed and allocated on the heap. This means they are managed by ARC and cleaned up when there are no more references to them.
^topicFibers. #
Fibers are freed by ARC just like any other object. Once there are no references to the fiber, it begins to release it's child references by unwinding it's call stack.
^topicHeap. #
Many object types in Cyber are small enough to be at or under 40 bytes. To take advantage of this, Cyber can reserve object pools to quickly allocate and free these small objects with very little bookkeeping. Bigger objects are allocated and managed by mimalloc
which has proven to be a fast and reliable general-purpose heap allocator.
Weak references. #
^topicPlanned Feature
Cycle detection. #
The cycle detector is also considered a GC and frees abandoned objects managed by ARC. Although weak references can remove cycles altogether, Cyber does not force you to use them and provides a manual GC as a one-time catch all solution.
Incomplete Feature: Only the main fiber stack is cleaned up at the moment.
To invoke the GC, call the builtin function: performGC
.
func foo():
-- Create a reference cycle.
var a = []
var b = []
a.append(b)
b.append(a)
-- Cycle still alive in the current stack so no cleanup is done.
var res = performGC()
print res['numCycFreed'] -- Output: 0
print res['numObjFreed'] -- Output: 0
foo()
-- `a` and `b` are no longer reachable, so the GC does work.
var res = performGC()
print res['numCycFreed'] -- Output: 2
print res['numObjFreed'] -- Output: 2
^topic
CLI. #
REPL. #
The REPL is started by running the CLI without any arguments:
cyber
The REPL starts new sessions with use $global
. This allows undeclared variables to be used similar to other dynamic languages:
> a = 123
> a * 2
`int` 246
When the first input ends with :
, the REPL will automatically indent the next line. To recede the indentation, provide an empty input. Once the indent returns to the beginning, the entire code block is submitted for evaluation:
> if true:
| print 'hello!'
|
hello!
Top level declarations such as imports, types, and functions can be referenced in subsequent evals:
> use math
> math.random()
`float` 0.3650744641604983
> type Foo:
| a int
|
> f = Foo{a: 123}
> f.a
`int` 123
Local variables can not be referenced in subsequent evals, since their scope ends with each eval input:
> var a = 123
> a
panic: Variable is not defined in `$global`.
input:1:1 main:
a
^
^topic
JIT compiler. #
Cyber's just-in-time compiler is incomplete and unstable. To run your script with JIT enabled:
cyber -jit <script>
The goal of the JIT compiler is to be fast at compilation while still being significantly faster than the interpreter. The codegen involves stitching together pregenerated machine code that targets the same runtime stack slots used by the VM. This technique is also known as copy-and-patch
. As the VM transitions to unboxed data types, the generated code will see more performance gains.
AOT compiler. #
The ahead-of-time compiler generates a static or dynamic binary from Cyber source code.
This is done by first compiling Cyber code into C code, and using a C compiler to generate the final binary.
The user can specify the system's cc
compiler or the builtin tinyc
compiler that is bundled with the CLI.
This is currently in progress.