Compile-Time Evaluation

Pluto's parser provides some powerful constructs which allow you to write code that will never be seen at runtime.

Function calls

Certain standard library functions can be called at compile-time, as long as the arguments are also known at compile-time, by using the "$" symbol before the function call.

local runtime = require("crypto").joaat("Hello, World!")
local compile = $crypto.joaat("Hello, World!")

assert(runtime == compile)

If you're unfamiliar with compile-time evaluation, this is essentially what the code turns into:

local runtime = require("crypto").joaat("Hello, World!")
local compile = 847757641 -- The JOAAT hash of "Hello, World!"

assert(runtime == compile)

This is available on preloaded Pluto libraries, such as:

• json
• base32
• base58
• base64
• crypto

And on the following functions:

• tostring
• utostring
• tonumber
• utonumber

Variables

Compile-time constant variables can be defined via the $define statement:

$define a = 123

This may seem identical to a local declared with the const attribute:

local a <const> = 123

However, $define also enforces that the assigned variable is a compile-time constant:

local a <const> = {}
$define a = {} -- variable was not assigned a compile-time constant value

Conditionals

If there is certain code you only want to have compiled in for a certain build, such as a debug build, you can use compile-time conditionals:

$define DEBUG = true

$if DEBUG then
    print("Script running in debug mode")
$else
    print("Script running in release mode")
$end

In this case, only one of the two paths will be compiled in; the rest will not take up any space.