A hacky way to hijack methods in the Haxe standard library

build.hxml

--macro haxe.macro.Compiler.addMetadata("@:build(Hacky.build())", "Math")
# Replace 'Math' with any class that you intend to hijack

Hacky.hx

package;

import haxe.macro.*;

class Hacky {

	public static function build() {
		var fields = Context.getBuildFields();
		for (field in fields) {
			if (field.name == "random") { // Here we target the `random()` method of the Math class.
				field.access.push(ADynamic);
			}
		}

		return fields;
	}
}

Main.hx

package;

class Main {

	public static function main() {

	}

	private static function __init__() : Void {
		Math.random = function() {
			// custom PRNG code here
		}
	}


}