Monkey

A interpreter language implementation in Go

1 Introduction

Monkey interpreter language which is implemented Go language. After typing monkey in terminal, you get into the monkey programming language.

$ ./monkey
Hello $Username! This is Monkey programming language!
Feel free to type in commnd
Enter "exit()" or CTRL+C to quit command interface
>>>

2 Syntax

2.1 Definition

using let as keyword, each line ends with ;.

>>>let a = 3;
>>>let b = 1.2;
>>>a+b
4.2

2.2 Arithmetic operations

monkey supports all basic arithmetic operation of int and float types. int type is represented by int64 and float type is represented by float64.

>>> let a = 3;
>>> let b = 1.2;
>>> a + b
4.2
>>> a - b
1.8
>>> a * b 
3.6
>>> a / b 
2.5

2.3 Builtin containers

monkey contains two builtin containers: array and map.

array

array is a list which organizes items by linear sequence. But types of items can be different from each other.

>>> let a = [1, 2.3, "array"];
>>> a 
[1, 2.3, array]
>>> let b = push(a, "another");
>>> b 
[1, 2.3, array, another]

map is treated as key-value container. please attention to that only boolean, int and string types can be used as key.

>>> let a = {"name":"moneky", true:1, 7:"sevent"};
>>> a
{name: monkey, true: 1, 7: seven}
>>> a["name"]
monkey
>>> a[true]
1
>> a[7]
seven
>>>let b = set(a, 8, "eight");
>>> b 
{name: moneky, true: 1, 7: sevent, 8: eight}

2.4 Builtin functions

len

yield the length of builtin containers.

first

yield the first element of array.

last

yield the last element of array.

rest

yield an array which excludes the first element.

push

push an elements into the array.

set

insert key value pair into the map

puts

print literal value of objects.

2.5 Function

monkey use fn as the definition of function. Apart from regular function using, monkey also includes high order function.

>>>let add = fn(a, b) { return a + b;};
>>> add(1,2)
3
>>>let addTwo = fn(a,b, f) { return 2 + f(a, b);};
>>>addTwo(1,2, add)
5

2.5 If-else statements

monkey supports if-else statements.

>>> let max = fn(a, b) { if (a > b) { return a;} else { return b; } };
>>> max(1, 2)
2

2.6 For-loop statements

monkey support for-loop statement.

>>> let sum = fn(x) { let i = 1; let sum = 0; for (i < x) { let sum = sum + i; let i = i+1; } return sum; };
>>> sum(100)
4950

3 Extensions

To make monkey interpreter language to be more powerfull, it is deserved improving it.

zzh1823/Monkey