Radl has reference transparence and detach thealgorithm from program, which make derivation of algorithm and program easy and guarantee the correctness of Apia program.

• Radl语言的引入使得算法和程序相分离，并具有引用透明性，这些都有利于算法和程序的推导，从而可保证作为系统输入的Apla程序的正确性。