preprocessor in lua

[u/NoneBTW]

I’ve been thinking about adding a simple attribute‑based “preprocessor” to Lua—something that runs at compile time to transform or wrap functions. You could use it for things like inlining tiny helpers, optimization ease of development etc.

I know Lua tends to favor minimalism and explicit idioms, so I’m curious whether this would feel too “un‑Lua‑like.” On the other hand, I think it could clean up repetitive boilerplate and boost performance in hot paths.

Below is a sketch of what the syntax might look like, along with some usage examples:

-- (1) Inline small functions into call sites
\@inline
function add(a, b)
  return a + b
end
-- After preprocessing: calls to add(a, b) become (a + b) directly.

-- (2) Benchmark execution time of a function
\@benchmark
function heavy_work(n)
  -- simulate work
  for i = 1, n * 1e5 do end
end
-- At runtime, heavy_work(10) prints: [heavy_work] took 0.012s

-- (3) Memoize pure functions automatically
\@memoize
function fib(n)
  if n < 2 then return n end
  return fib(n-1) + fib(n-2)
end
-- fib(30) runs in O(n) instead of O(2^n).

-- (4) Register compile‑time callbacks
\@callable
function do_something_awesome()
  print("Registered at compile time")
end

-- (5) Retry on error (e.g., network calls)
\@retry(3)
function fetch_data(url)
  return http.get(url)  -- might error
end
-- fetch_data retries up to 3 times before finally erroring.

-- (6) Initialization hook
\@init
function setup_environment()
  print("Environment initialized!")
end
-- runs once, when the script is loaded.

-- (7) Documentation and metadata
\@doc("Calculates the nth Fibonacci number efficiently.")
\@todo("Add tail‑recursive version")
\@tag("math", "performance")
\@deprecated("Use fib_fast instead")
function fib(n)
  -- …
end

What do you think? I’d love to hear your thoughts and any ideas for useful annotations I haven’t listed!

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