Grammar and Data Types

In this section, we will discuss the basic syntax and variable declarations of WhirlScript.

Basics

WhirlScript is case-sensitive and uses the UNICODE character set.

In WhirlScript, instructions are called statements and are separated by semicolons ;.

Comments

The syntax of WhirlScript comments is similar to many languages:

// Single line comment

/* This is
   a multi-line comment.
 */

These will be skipped during the code compilation process. However, if you enable withComment in the compilation options, these comments will be included in the output.

Declarations

There are four states of quantities in WhirlScript:

• Compile-time variables: Can be modified and used during compilation;
• Compile-time constants: Can be used during compilation, cannot be modified;
• Runtime variables: Can be modified and used at runtime;
• Runtime constants: Can be used at runtime, cannot be modified.

Runtime quantities can be declared with keywords var and const:

• var: Declare a runtime variable, optionally initialize a value.
• const: Declare a runtime constant.

Runtime variables

var v: int = 1;

Runtime constants

const v: int = 1;

For compile-time quantities, you need to add keyword macro.

Compile-time variables

macro var v: int = 1;

Compile-time constants

macro const v: int = 1;

Variables

In applications, variables are used as symbolic names for values. The name of a variable is called an identifier, which needs to follow certain rules.

A WhirlScript identifier must start with a letter; subsequent characters can also be numbers (0-9). Because the JavaScript language is case-sensitive, letters can be uppercase letters from "A" to "Z" and lowercase letters from "a" to "z".

Like other languages, most operators cannot be included in the name. What's different is that these symbols, which other languages might allow, are also not allowed:

• $
• _

Why?

Since the identifier of variables in shell is the $ symbol, you cannot use it as a name.

The _ symbol is used to identify scopes and other internal uses, so it cannot be used as a name either.

Note that these two symbols will be parsed as ordinary operators.

At the same time, the behavior of using keywords as identifiers is undefined.

Examples of legal identifiers: NumberHits, temp99.

Declaring Variables

You can declare a variable in this way:

var num: int = 1;

Where var indicates that a runtime variable is declared, num is the identifier of the variable, : int indicates that the variable type is int, and = 1 initializes this variable to a value (here it is 1).

If initialization is included, the variable type is optional (inferred by the compiler).

In some cases, you must specify the type to get the result you want:

var aNum: int = 1;
var aString: string = aNum;  // Get "1".

This will be mentioned in Conversion of Data Types.

For all variables (including compile-time and runtime variables), initialization is optional.

Variable Evaluation

For variables declared with the var statement, if no initial value is assigned, accessing its value will get a default value. The default value is different depending on the type.

Accessing an undeclared variable will cause an error.

No Mangling

You can use the @noMangle annotation to disable mangling:

⚠️ Warning

You can only declare a runtime quantity no mangling. The same as function.

See Annotations for more information about annotations.

@noMangle var g: string = "I am g";


bat raw("echo %g%\n");  // Output g in bat.
sh raw("echo $g\n");    // Output g in sh.

// More recommended writing
raw(`echo ${g}\n`);   // This does not need to judge the syntax environment, it can be called directly.

// Or directly
println(g); The built-in println function.

You can directly call it in raw statements. But we recommend using template syntax to directly splice commands.

Constants

You can create a read-only constant with the keyword const. The naming rules for constant identifiers are the same as for variables.

const version = "1.1.0";

All constants (including compile-time and runtime constants) cannot change their values by reassigning, nor can they be redeclared during code execution. It must be initialized to some value.

You can choose to omit the type (inferred by the compiler) or explicitly specify it.

In the same scope, you cannot use a name that is the same as a variable name or function name to name a constant.

Data Structures and Types

Data Types

WhirlScript defines three data types:

• boolean: Boolean value, with 2 values: true and false.
• int: Integer, for example 0, 42, 1000.
• string: String, for example "string".

Why no float?

bat only provides integer operations. For compatibility, we can only discard this part.

If you need to get several decimal places, multiply both the divisor and the dividend by 10 to the nth power, and then cut off the tail.

The shell provides support for floating point numbers. If you need to use it, use it in the exec function.

Conversion of Data Types

WhirlScript is statically typed, which means that the type of a variable is immutable.

For example, you cannot assign a string value to an int type variable in this way:

var n: int = 12;
n = "string";   // Error!

Implicit Conversion

In this case, there will be no error:

var s: string = "string";
s = 12;

Here an implicit conversion has occurred. There are three situations for implicit conversion, respectively:

• Boolean to integer: false will be converted to 0, true will be converted to 1.
• Boolean to string: false will be converted to "0", true will be converted to "1".
• Integer to string: For example, 123 will be converted to "123".

Even if you directly call it in raw statements, it will be the same.

Why?

In the underlying implementation, all quantities are strings.

The underlying implementation of Boolean values is "0" and "1".

The underlying implementation of integers is the corresponding string.

Type Assertion

Implicit conversion can only be upward conversion.

If you need to convert in reverse, you need type assertion. The premise is that you are very sure that this is convertible.

Type assertion is marked with <>, for example:

var n: int = <int>"123";

The compiler will not check whether your conversion is legal. Please use it cautiously.

Literals

In WhirlScript, you can use various literals. These literals are fixed values given in the script literally, not variables.

For example 1, true, "str".