Standard Library

Built-in Functions

In LuneScript, the following Lua-compatible or specialized built-in functions are available.

Function Name	Description
`print(...)`	Outputs arguments to the standard output.
`type(val)`	Returns the type name of the value as a string (e.g., "int", "str", "table", "nil").
`tostring(val)`	Converts the value to a string.
`tonumber(val, base)`	Converts a string to a number. The base (2-36) can be specified with `base`. Returns `nil` on failure.
`error(msg)`	Raises an error.
`assert(cond, msg)`	Raises an error if the condition is `false`.
`_load(code, name)`	Loads a Lua code string and returns an executable function. `name` is the chunk name.
`unwrap val [default]`	Converts a Nilable type to a Non-nilable type. If `default` is provided, it returns the default value if the input is `nil`.

String Operations (str type methods)

The string type str can use functions from Lua's string library as methods.
The format operator % is also available.

let text = "hello world";
print( text.upper() );  // HELLO WORLD
print( text.sub( 1, 5 ) ); // hello (LuneScript/Lua indexing starts at 1)
print( #text );    // 11 (Get length with #text)
print( text.find( "world", 1, true ) );

let formatted = "Value: %d" ( 123 ); // Format
print( formatted );

Using Lua Standard Libraries

Lua standard libraries (math, os, io, string, table) are available by making a module declaration.
LuneScript does not have built-in features that directly wrap these, but they can be used by defining them as follows.

Example of Math Library

module Math require "math" {
    pub static let pi: real;
    pub static fn sin( x:real ): real;
    pub static fn cos( x:real ): real;
}
print( Math.sin( Math.pi ) );

IO (Input/Output)

File operations use Lua's io library. Depending on the environment, you may need a module declaration, or the built-in io variable may already be available.

// Example of File Reading
if! let mut file = io.open( "test.txt", "r" ) {
    if! let txt = file.read( "*a" ) {
        print( txt );
    }
    file.close();
}

Available IO features may vary depending on the transcompilation target environment (Lua, Go).