参考用Go语言自制解释器实现的一门带命令行的语言， 具体特性如下：
- 类C语法
- if else
- while
- 函数定义
- 变量绑定
- 整型和布尔型
- 算术表达式
- 函数和高阶函数
- 闭包
- 字符串
- 数组
- Hash
- 内置函数
- len: 求数组和字符串长度
- first: 求数组第一个元素
- push: 向数组结尾添加一个元素
- print: 向标准输出打印数据
- time: 返回当前时间戳
- 宏
git clone
cd monkey-lang
mvn clean package
java -jar target/monkey-lang.jar- 变量绑定
>>> let a = 1;
>>> a
1
>>> let b = 2
>>> b
2
>>> let a = 1 > 2
>>> a
false
>>> - 函数
>>> let fib = fn(x) {
if (x==0) {
return 0;
} else {
if (x==1) {
return 1;
} else {
return fib(x-1) +fib(x-2);
}
}
}
>>> fib(1)
1
>>> fib(2)
1
>>> fib(10)
55
>>> fib(20)
6765
>>>
>>> fn fib(x) {
if (x==0) {
return 0;
} else {
if (x==1) {
return 1;
} else {
return fib(x-1) +fib(x-2);
}
}
};
NULL
>>> fib(1);
1
>>> fib(2);
1
>>> fib(3);
2
>>>- 高阶函数
>>> let twice = fn(func, x) {
return func(func(x));
}
>>> let addOne = fn(x) {
return x+1;
}
>>> twice(addOne, 1)
3
>>> twice(addOne, 2)
4
>>>- 字符串
>>> let hello = "hello there, fellow monkey users and fans"
>>> hello
hello there, fellow monkey users and fans
>>> "hello world"
hello world
>>> let sayHello = fn() {
"Hello!";
}
>>> sayHello()
Hello!
>>> let greeter = fn(greeting) {
fn(name) {
greeting + " " + name +"!";
}
}
>>> let hello = greeter("hello")
>>> hello("feng")
hello feng!
>>>- 数组
>>> let myArr = [1+2, 2+3, fn(x){return x*x}]
>>> myArr[0]
3
>>> myArr[1]
5
>>> myArr[2](2)
4
>>> len(myArr)
3
>>> first(myArr)
3
>>> let another = push(myArr, 4)
>>> another
[3,5,fn(x) {
return (x * x);
},4]
>>>- Hash
>>> let myHash = {true:"yes, boolean", 99:"correct, an integer"};
>>> myHash[true]
yes, boolean
>>> myHash[99]
correct, an integer
>>> myHash[5>1]
yes, boolean
>>> myHash[100-1]
correct, an integer
>>> let people = [{"name":"alice", "age":24}, {"name": "anna", "age": 28}];
>>> people[0]["name"]
alice
>>> people[0]["age"]
24
>>> people[1]["age"]
28
>>> people[1]["name"]
anna
>>>
>>> let getName = fn(person) {return person["name"];};
>>> getName(people[0])
alice
>>> getName(people[1])
anna
>>>
>>> let newPerson = {};
>>> let newPerson = put(newPerson, "name", "bob")
>>> let newPerson = put(newPerson, "age", 25)
>>> let people = push(people, newPerson)
>>> len(people)
3
>>> people[2]["name"]
bob
>>> people[2]["age"]
25
>>>- 内置函数
>>> len("1234")
4
>>> let four = "2"
>>> len(four)
1
>>>
>>> print("hello world");
hello world
>>> time()
2023-04-03 21:42:42
>>> - 宏
>>> let reverse = macro(a, b) {
quote(unquote(b)-unquote(a));
};
>>> reverse(2+2, 10-5)
1
>>> let evalSecond = macro(a, b){
quote(unquote(b));
};
>>> evalSecond(print("not printed"), print("printed"))
printed
>>>
>>> let unless = macro(condition, consequence, alternative) {
quote(if (!(unquote(condition))) {
unquote(consequence);
} else {
unquote(alternative);
});
};
>>> unless(10<5, print("not greater"), print("greater"))
not greater
>>> unless(10>5, print("not greater"), print("greater"))
greater
>>>- 循环
>>> let loop = fn() {
let i=0;
while(i<3) {
print(i);
let i=i+1;
}
};
NULL
>>> loop();
0
1
2
NULL
>>> loop();
0
1
2
NULL
>>>
>>> let loop = fn(i) {
if (i<2) {
print(i);
loop(i+1);
}
};
NULL
>>> loop(0)
0
1
NULL
>>>- 词法分析器 -> 递归下降
- 语法分析器 -> Pratt Parser
- 解释器 -> 树遍历解释器
- 命令行 -> Jline3
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