From 052144cabb126efe925a96f8a0597a0f2005d206 Mon Sep 17 00:00:00 2001 From: lemon Date: Mon, 23 Feb 2026 20:36:05 +0100 Subject: add metalang99 testsuite (preprocessor stress testing) --- test/external/metalang99/optimization_tips.md | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) create mode 100644 test/external/metalang99/optimization_tips.md (limited to 'test/external/metalang99/optimization_tips.md') diff --git a/test/external/metalang99/optimization_tips.md b/test/external/metalang99/optimization_tips.md new file mode 100644 index 0000000..261cbe8 --- /dev/null +++ b/test/external/metalang99/optimization_tips.md @@ -0,0 +1,24 @@ +# Optimization tips + +_This document describes a few optimization tips when using Metalang99._ + +Generally speaking, the fewer reduction steps you perform, the faster you become. A reduction step is a concept defined formally by the [specification]. Here is its informal (and imprecise) description: + + - Every `v(...)` is a reduction step. + - Every `ML99_call(op, ...)` induces as many reduction steps as required to evaluate `op` and `...`. + +To perform fewer reduction steps, you can: + + - use `ML99_callUneval`, + - use plain macros (e.g., `ML99_CAT` instead of `ML99_cat`), + - use optimized versions (e.g., `ML99_listMapInPlace`), + - use tuples/variadics instead of lists, + - call a macro as `_IMPL(...)`, if all the arguments are already evaluated. + +
+ Be careful with the last trick! + +I strongly recommend to use the last trick only if `X` is defined locally to a caller so that you can control the correctness of expansion. For example, `X` can become painted blue, it can emit unexpected commas, the `#` and `##` operators can block expansion of parameters, and a plenty of other nasty things. +
+ +[specification]: spec/spec.pdf -- cgit v1.2.3