README.md: mention boolean types

README.md

@@ -3,27 +3,39 @@
 [![Latest Release](https://img.shields.io/github/v/release/Muqsit/arithmexp)](https://github.com/Muqsit/arithmexp/releases/latest)
 
 [`arithmexp`](https://github.com/Muqsit/arithmexp) is a powerful mathematical expression parser and evaluator library for PHP with support for [variable substitution](https://github.com/Muqsit/arithmexp#evaluating-a-mathematical-expression), [constant declaration](https://github.com/Muqsit/arithmexp/wiki), [deterministic and non-deterministic function registration](https://github.com/Muqsit/arithmexp/wiki), and more.
-Test out the parser on the [**demo site**](https://arithmexp.pages.dev/)!
+
+> [!TIP]
+> Try out arithmexp parser on the [**demo site**](https://arithmexp.muqs.it/)!
 
 ## Installation with composer
 ```
 composer require muqsit/arithmexp
 ```
 
 ## Evaluating a mathematical expression
-To evaluate a mathematical expression, a [`Parser`](https://github.com/Muqsit/arithmexp/blob/master/src/muqsit/arithmexp/Parser.php) instance must first be constructed.
-The mathematical expression string must be passed in `Parser::parse()` to obtain a reusable [`Expression`](https://github.com/Muqsit/arithmexp/blob/master/src/muqsit/arithmexp/expression/Expression.php) instance.
-The value of the mathematical expression can then be evaluated by invoking `Expression::evaluate()`.
+To evaluate a mathematical expression, create a [`Parser`](https://github.com/Muqsit/arithmexp/blob/master/src/muqsit/arithmexp/Parser.php) and invoke `Parser::parse()` with an expression string to obtain a reusable [`Expression`](https://github.com/Muqsit/arithmexp/blob/master/src/muqsit/arithmexp/expression/Expression.php) object.
+`Expression::evaluate()` returns the value of the expression.
 ```php
 $parser = Parser::createDefault();
 $expression = $parser->parse("2 + 3");
 var_dump($expression->evaluate()); // int(5)
+
+$expression = $parser->parse("mt_rand()");
+var_dump($expression->evaluate()); // int(1370501507)
+var_dump($expression->evaluate()); // int(1522981420)
 ```
 
-To substitute values of variables that occur within the supplied expression, an `array<string, int|float>` must be passed to `Expression::evaluate()`.
+Variables may be substituted at evaluation-time by passing an `array<string, int|float|bool>` value to `Expression::evaluate()`.
 ```php
 $expression = $parser->parse("x + y");
 var_dump($expression->evaluate(["x" => 2, "y" => 3])); // int(5)
 var_dump($expression->evaluate(["x" => 1.5, "y" => 1.5])); // float(3)
+
+$expression = $parser->parse("a > b or c");
+var_dump($expression->evaluate(["a" => 1, "b" => 2, "c" => true])); // bool(true)
 ```
-The return value type of the evaluation is consistent with that of PHP's. As such, `int + int` returns an `int` value, whereas a `float + int|float` returns a `float` value. See documentation notes in the [**wiki**](https://github.com/Muqsit/arithmexp/wiki) for more details.
+The return value type of the evaluation is consistent with that of PHP's—`int + int` returns an `int` value, while `float + int|float` returns a `float` value.
+`bool + bool` returns an `int` value, while `int || int` returns a `bool` value.
+
+> [!NOTE]
+> Check out the [**wiki**](https://github.com/Muqsit/arithmexp/wiki) for documentation notes and further implementation details.