package coffee.liz.lambda.eval;

import coffee.liz.lambda.ast.Expression;

/**
 * Represents a runtime value produced by evaluation.
 */
public sealed interface Value permits Value.Closure, Value.Application, Value.Free {

	/**
	 * A closure capturing an environment, parameter, and body.
	 *
	 * @param env
	 *            the captured environment
	 * @param parameter
	 *            the bound parameter name
	 * @param body
	 *            the lambda body expression
	 */
	record Closure(Environment env, String parameter, Expression body) implements Value {
	}

	/**
	 * A symbolic application of a function to an argument.
	 *
	 * @param function
	 *            the function
	 * @param argument
	 *            the argument
	 */
	record Application(Value function, Value argument) implements Value {
	}

	/**
	 * A free variable.
	 *
	 * @param name
	 *            the variable name
	 */
	record Free(String name) implements Value {
	}
}