Lua::StackMixin::FunctionSupport

Registers a Crystal Proc as a global Lua function under the given name.

Argument types come from the proc's signature: each Lua argument is converted to the matching Crystal type before the proc is called, and the proc's return value is pushed back onto the Lua stack. A proc returning Nil produces no Lua return value.

lua = Lua.load

# inline proc literal
lua.function "add", ->(x : Float64, y : Float64) { x + y }
lua.run "return add(3, 4)" # => 7.0

# closure over local state
counter = 0
lua.function "tick", -> { counter += 1; nil }
lua.run "tick(); tick()"
counter # => 2

# method pointer
def greet(name : String)
  "Hi, #{name}"
end

lua.function "greet", ->greet(String)
lua.run "return greet('Lua')" # => "Hi, Lua"