islclosure - Mintlify Starter Kit

Tells you whether a function was written in Luau.

islclosure(func: function): boolean

Most commonly used to find user-script functions and look inside them.
For example, getconstants only works on Luau closures:

for _, fn in ipairs(getgc()) do
    if type(fn) == "function" then
        if islclosure(fn) then
            -- it's a LocalScript's/ModuleScript's Luau function!
            for i, k in ipairs(getconstants(fn)) do
                print(`constant {i}: {tostring(k)}`)
            end
        else
            -- it's an internal roblox's engine C function, pass
        end
    end
end

Parameters

Parameter	Type	Description
`func`	`function`	The function to check.

Returns

true if func is a Luau closure, false if it’s a C closure.

Example

local isL = islclosure(print)

local luaclosure = newlclosure(function()
    return "new"
end)
local luaclosure2 = function()
    return "also new"
end
local cclosure = newcclosure(function()
    return "old ahh"
end)

print(islclosure(luaclosure))  -- true
print(islclosure(luaclosure2)) -- true
print(islclosure(cclosure))    -- false

Lua closures are user-defined or script-defined Luau functions.