FORH在锈蚀性状系统中的实施

铁锈的特征系统是图灵完整的。该箱采用特征求值的原则来实现四次评价的必备特征，并提供了四次评价的原则！将语法转换为特征表达式的宏。

这里是一个简单的阶乘实现，这里唯一的非标准单词是pred，它是一个减运算符，相当于1-：

Fourth！(：阶乘(n--n)1交换fact0；：fact0(n n--n)dup 1=if drop Else DUP ROT*SWAP Pred fact0 Then；5阶乘。)；

这个可以打印120。正如您所看到的，您不仅可以轻松地定义函数，甚至还可以进行条件递归！现在看看编译成特征表达式后的样子(由Cargo Expand提供)：

发布特征阶乘{type Result；}为节点实施<；V，N&>；阶乘，其中Self：One，<；Self As One>；：：Result：SWAP，<；<；Self As>；：：Result AS SWAP>；：：Result：Fact0，{type Result=<；<；：：Result As One>；：：Result As}酒吧特性事实0{类型结果；}为节点<；V，N&>；实施<；V，N&>；fact0，其中SELF：DUP，<；SELF AS DUP&>；：：RESULT：ONE，<；<；SELF AS DUP&>；：：RESULT AS ONE；：：RESULT：EQ，<；<；：：RESULT AS ONE&gT；Self As DUP&>；：：Result As EQ&>；：Result As iff&>；：：Result：Drop，<；<；Self As DUP&>；：Result As EQ&>；：：Result As Drop&>；：：Result AS DUP&>；：：Result AS DUP&>；<；<；Self as DUP>；：：Result As Drop&>；：：Result As DUP&>；：：Result As DUP&>；：：Result AS DUP&>；<；<；：：Result as Else&>；：Result as Else As DUP&>；：：Result as Else As DUP&>；：Result As EQ&>；：Result As Iq&>；：Result As Drop&>；：Result As Else As DUP&>；：：Result As DUP&>；：：Result As Else&>；：Result As Else&>；：Result As DUP&>；：：Result As Else&>；：Result As DUP&>；：：Result As DUP&>。<；<；SELF AS DUP&>；：RESULT AS EQ&>；：RESULT AS EQ&>；：：RESULT AS DUP&>；：：RESULT AS ELELF&>；：RESULT AS ROT&>；：：RESULT：MULT，<；<；SELF AS DUP&>；：：RESULT AS ONE>；：：Result as DUP&>；：：Result as One>；：：Result as Elf&>；：Result as DUP&>；：Result as DUP&>；：Result as Rot&>；：Result as MULT&>；：：Result：SWAP，<；<；<；Self AS DUP&>；：Result As One>；：Result AS EQ&>；：Result As If>；：Result As If>；：Result As Iq>；：Result as Elf>；：Result as Iq>；：Result as Iq>；：：：：结果为多个交换&>；：：结果为多个交换&>；：：结果为多个交换&>；：：结果为多个交换&>；：：结果为自身为重复&>；：：结果为一个：结果为等式；：：结果为删除&>；：：结果为删除&>；：：结果为丢弃(&>t；：：结果为删除>；：：结果为删除>；：：结果为删除>；：：结果为删除；：：Result as pred&>；：：Result as pred&>；：Result as<；<；&>；：Result As One&>；：Result As Eq&>；：Result As Iq&>；：Result As Drop&>；：：Result As Pred&>；：：Result as Else&>；：：Result as Pred&>；：：Result as Fact0&>；：：Result：Then{TYPE RESULT=<；<；SELF AS DUP&>；：：RESULT AS OUT&>；：：RESULT AS EQ&>；：RESULT AS EQ&>；：：RESULT AS DUP&>；：Result AS DUP&>；：Result AS ROT&>；：Result AS MULT&>；：：Result AS SWAP&>；：：Result AS Pred>；：：Result AS Fact0>；：：Result AS Then>；：：Result as DUP&>；}println！("；{}&34；，<；<。：：result：：eval())；

正如您在上面看到的，实际上支持相当多的内容。特征评估中的每个操作都会重新导出到堆栈上(除非以不同方式完成)，并且提供了一汽额外的堆栈操作。有关详细信息，请参阅文档。