Attributes
An attribute is metadata applied to the file or to a statement. Attributes are modeled on attributes in Rust
Inner attributes, written with a bang (!) after the hash (#), apply to the item that the attribute is declared within. Outer attributes, written without the bang after the hash, apply to the statement that follows the attribute.
syntax
inner = "#![" attributes "]"
outer = "#[" attributes "]"
attributes = (
varname [= value]
|
varname "(" attribute1, attribute2, ..., attributeN ")"
)value = ( number | " string ")
binary
Unlike JavaScript, by default, a kaoscript file is a module.
A module can not be executed by the command line kaoscript, it will need to be imported from another file.
For a kaoscript file to be executed as binary, it would need the attribute #![bin].
#![bin]
extern console
console.log('Hello World!')
conditional compilation
Condition compilation allows to transpile the code depending of the targeted engine.
// if the engine is IE (*trident*) or Safari 8 or under (*lte(jsc-v8)*)
#[if(any(trident, lte(jsc-v8)))]
impl String {
endsWith(value: String): Boolean => this.length >= value.length && this.slice(this.length - value.length) == value
}
#[else]
disclose String {
endsWith(search: String): Boolean
}
By default, the only available targets are ecma-v5 and ecma-v6.
@kaoscript/target-commons provides those additional targets.
operators
| operator | description |
|---|---|
any(item1, ..., itemN) | true if at least one item is true |
all(item1, ..., itemN) | true if all the items are true |
none(item1, ..., itemN) | true if none of the item are true |
one(item1, ..., itemN) | true if only and only one item is true |
lt(item) | less than |
lte(item) | less than or equals |
gt(item) | greater than |
gte(item) | greater than or equals |
rules
kaoscript allows to apply some rules about the code.
| rule | desciption |
|---|---|
| no-undefined | all variables must have been defined |
| ignore-misfit | accessing an unmatched member doesn't throw an error |
| non-exhaustive | the declaration is not exhaustive; access to unmatched members will not throw an error |
no-undefined
By default, undefined variables assigned will be created.
name = 'John'
// like: let name = 'John'
You can change this behaviour with the rule no-undefined.
#![rules(no-undefined)]
func foobar() {
x = 42
// throw the ReferenceException error: "x" is not defined
console.log(x)
}
ignore-misfit
By default, if a member (field/method for a class, variable/function for a namespace or field for an enum) or a function is accessed and can't be matched with the given arguments, it will throw an error.
The rule ignore-misfit disables this behaviour and ignores mismatched members or functions.
non-exhaustive
The rule non-exhaustive can only be applied to external declarations or to the statement disclose.
By default, external declarations without any definitions are considered as non-exhaustive, whereas those with a definition are considired as exhaustive.
The statement disclose forces the associated declaration to be considired as exhaustive.
extern namespace console
// console: non-exhaustive
console.log('foobar')
extern namespace console {
func log(...)
}
// console: exhaustive
console.log('foobar')
// print: foobar
console.debug('foobar')
// throw an error
extern class Foobar
// Foobar: non-exhaustive
Foobar.log('foobar')
extern class Foobar
// Foobar: non-exhaustive
disclose Foobar {
log(...)
}
// Foobar: exhaustive
console.log('foobar')
// print: foobar
console.debug('foobar')
// throw an error
runtime
kaoscript needs a runtime to add dynamics functions on classes (Helper) and to do type checking (Type).
The runtime is imported only when it's needed.
The default runtime is @kaoscript/runtime and provides only the bare minimum.
But you can provide your own runtime with the following attributes
#![runtime(package="@kaoscript/runtime")]
#![runtime(type(alias="Type", member="Type"))]
#![runtime(helper(alias="Helper", member="Helper"))]