Evaluate code block in a function parameter in lua

Question

I wasn't really sure how to title the question, but consider the following lua code:

print(function ()
    s = ""
    for i = 1, 10 do
      s = s..tostring(i)
    end
    return s
  end)

But this prints only the function address, since function() returns a closure. Is there a way to evaluate the anonymous function? Like in scheme where I can embrace the lambda in additional brackets?

((lambda ()(display "Hello World")))

Of course I know, I could define the function beforehand and call it later, but I was just curious if this is possible in lua. Thanks in advance for all replys.

Answer 1

You need to wrap the function definition in parentheses and then call it by adding () after. Putting this in the Lua interpreter:

> print((function ()
    s=""
    for i=1,10 do
       s=s..tostring(i)
    end
    return s
  end)())

gives the following output

> 12345678910

Answer 2

If this is a global behaviour you want, the simplest solution would be to hook print so that it evaluates any functions passed to it. That way you can simply leave the call sites as lambdas.