A simple programming language

Introduction

Bean is a Dynamic Programming Language which developed by myself at work off hours. The reason of why it called Bean is that the company which I am working for named Beansmile. That is the most primary reason. May be it will not be a good programming language in the world but it must be a meaningful language to me. Because it is the first programming language which I make.

I don't know too much about the principle of compiling, So I try my best to make it simple. Even Though it isn't means that Bean is a DSL--Domain Specific Language, no, it is a GPL--General Purpose Language, like Ruby, Python, JavaScript, Java, Go, etc.

There is a simple preview for Bean.

1. A programming language without class keyword.
2. An OOP(Object-oriented programming) language base on prototype.
3. The syntax will be similar to JavaScript.
4. Just nil and false will be the falsy value.
5. The variable name or function name can contain ?.
6. The basic data type include Number, String, Bool, Array, Hash, Function.
7. Stack-Based Virtual Machine.

And for display the inheritance relationship, I make a diagram.

Install Guide

Thanks for the help from GUN, we can easily install bean in our computer. Unfortunately I just test it in my Mac book and some Linux distribution, like Ubuntu.

1. Clone from github

git clone [email protected]:lanzhiheng/bean.git && cd ~/bean

2. Configure the project to generate makefile

./configure

3. Make it to start compiling

make

4. Run the bean

After that you will get the Bean binary file named bean in current directory. Just run it. I have design two mode for it. Script-Mode and REPL

Let's check REPL mode first

➜ ./bean
> var a = "hello"
=> "hello"
> print(a)
hello
=> nil
> 1 + 22
=> 23
> (10 - 20) * 100
=> -1000

it is very convenience for checking the basic statement of Bean. But if you want to write multiline source code you should use Script-Mode.

Your first Bean script.

// first-script.bn
fn firstScript() {
  var a = 100 + 90;
  print(a)
  "Hello World"
}
var b = firstScript()

print("The value of variable b is " + b)

Run the script

➜ ./bean first-script.bn
190
The value of variable b is Hello World

Basic syntax for Bean

In this part I will show you some Syntax for Bean. About variables' assigning, function's definition and calling, Basic operation and so on.

1. Variables

I don't set constant mechanism in Bean, so now it just support variable. you just need the var keyword to define an variable, by default nil will assign to it.

> var a = 200
=> 200
> var b
=> nil

If you want to access a undefined variable it will raise error.

> c
EvalError: Can't reference the variable before defined.
  from REPL:2

2. Basic Type

There are six basic type in Bean, they are number, boolean, string, array, hash and nil, respectively. We can inspect the type of a variable by typeof statement.

> var num = 1
=> 1
> typeof num
=> "number"

> var str = "lan"
=> "lan"
> typeof str
=> "string"

> var bool = true
=> "boolean"
> typeof bool
=> "boolean"

> var n = nil
=> nil
> typeof n
=> "nil"

> var array = []
=> []
> typeof array
=> "array"

> var hash = {}
=> {}
> typeof hash
=> "hash"

> var a = fn() {}
=> [Function a]
> typeof a
=> "function"

Otherwise, including some build-in library, the instances of them or themself are hash type.

> typeof Date
=> "hash"
> typeof Regex
=> "hash"
> typeof HTTP
=> "hash"
> typeof Date.build()
=> "hash"
> typeof Regex.build("dd")
=> "hash"

Condition statement

In Bean, only false and nil will be seen as false value. If you want to make your condition statement work as your expectation, you need to understand it.

> !""
=> false
> !false
=> true
> if (true) { print("hello") }
hello
=> nil
> if (false) { print("hello") }
=> nil

You also can append else branch after the if branch.

var a = 100

var greater
if (a > 10) {
  greater = true
} else {
  greater = false
}

print(greater) // => true

Of course we are supporting else if branch, but in Bean, similar to Ruby, we use the keyword elsif, So

var b = 100
if (b > 200) {
  b = 200
} elsif (b > 30) {
  b = 30
} else {
  b = 0
}

print(b) // => 30

I have talk about that the it is a statement, so it will return something. If you want to get return value of the condition statement you can assign it to variable.

var c = 100
var result = if (c > 200) {
  "Result is 200"
} elsif (c > 10) {
  "Result is 10"
} else {
  "Result is 0"
}
print(result)

If you run this script with Bean's Script-Mode, you will get the result "Result is 10". That is because the last statment in the branch will be seen as the return value. But you can't return the special value explicitly when outside the function.

// return-outside-function.bn
var d = 300
var result = if (d > 30) {
  return "Return Ahead"
  print("Not run")
} else {
  return "Result is 0"
}
print(result)

will get the result

RuntimeError: Can not return outside the function
  from return-outside-function.bn:8
[1]    83606 abort      ./bean return-outside-function.bn

loop statement

We just support the basic while loop statement in bean. Let me show you some code

// basic-loop.rb
var i = 0

while(i < 6) {
  i++;
}

print(i) // => 6

Also you can use keyword to break the loop in advance.

// basic-loop.rb
var i = 0p

while(i < 6) {
  i++;
  if (i > 3) { break }
}

print(i)

Or you can write a nesting one

// nesting-loop.bn
var m = 0
var total = 0

while(m < 2) {
  var n = 0
  while(n < 9) {
    total += n;
    n++
  }
  m++;
}
print(total) // => 72
print(m) // => 2

We also support do-while statement

var i = 100
var run = false

do {
  run = true
} while(i > 100)

print(run) // => true

Function Definition and Calling

We use keyword fn to define a function in Bean. So you can define a function like below.

fn add(a, b, c) {
  a + b + c
}

add(1,2,3) // => 6
add(1) // => 1nilnil
add(1, 2) // => 3nil

As you can see if you missing some parameters they will auto assign by nil. In this case they will contact by + operator.

That is one of the method to call function, you also can use call or apply to invoke. Similar to javascript the first paramater of call or apply will be seen as self.

print(add.call(nil, 1,2,3)) // => 6
print(add.call(nil, 1)) // => 1nilnil
print(add.call(nil, 1,2)) // => 3nil

print(add.apply(nil, [1,2,3])) // => 6
print(add.apply(nil, [1])) // => 1nilnil
print(add.apply(nil, [1,2])) // => 3nil

Let's check the self's behavior in function. As this in JavaScript.

fn returnSelf() {
  self
}

print(returnSelf.call("hello")) // => hello
print(returnSelf.call(12)) // => 12

fn returnAttributeName() {
  self['name']
}

print(returnAttributeName.call({ name: 'lanzhiheng' })) // => lanzhiheng

fn returnValueofIndex(a) {
  self[a]
}

print(returnValueofIndex.call(["Ruby", "JavaScript", "Go"], 2)) // => Go
print(returnValueofIndex.apply(["Ruby", "JavaScript", "Go"], [0])) // => Ruby

OK, that is all for function. If you are familiar to JavaScript, that will be so easy for you.

It should be noted that, apply or call method just can use in customized function, it will not work in system's build-in function. Because the prototype of them are different.

> print.__proto__
=> {id: [Primitive function], toString: [Primitive function], __proto__: [Primitive getter]}
>  print.__proto__.__proto__
=> nil
> fn a() {}
=> [Function a]
> a.__proto__
=> {call: [Primitive function], apply: [Primitive function]}
> a.__proto__.__proto__
=> {id: [Primitive function], toString: [Primitive function], __proto__: [Primitive getter]}
> a.__proto__ == Function
> true
> Function.__proto__ == Meta
=> true
> print.__proto__ == Meta
=> true

The prototype of normal function is Function, but of system's built-in function is Meta. Meta is the prototype of Function. So the built-in function don't have call or apply method which store in prototype Function.

Number

Number value

Not only in Bean, almost every programming language contains the number type. Similar to JavaScript, Bean store all the number value as float, even it has the integer schema. Let me so you some cases.

> var a = 10
=> 10
> a = 1e3
1e3
=> 1000
> a = 11.1
=> 11.100000
> a = 11.1e2
=> 1110

Bean doesn't support the octal but hex. So you can define the number like below.

> 022
=> 22
> 018
=> 18
> 0x01
=> 1
> 0x10
=> 16

Number formatting

We provide a few method to format the number. For example if you want to make a string which has fixed bits after the point. You can use toFixed/1 method.

> var a = 10.33333333
=> 10.333333
> a.toFixed(1)
=> "10.3"
>  a.toFixed(2)
=> "10.33"
> a.toFixed(100)
=> "10.3333333300000003163177098031155765056610107421875000000000000000000000000000000000000000000000000000"

If you don't pass paramater, number 2 will be the default value.

> var a = 100
=> 100
> a.toFixed()
=> "100.00"
> a.toFixed('100')
The paramter which you passed must be a number.
> a.toFixed(-10)
=> "100.0000000000"
> a.toFixed(2.3)
=> "100.00"

Otherwse, As you can see in the example, above, The parameter which you are passing must be a number value. If you passed the positive float as the parameter we will convert it to integer as well as if you passed the negative one we will get the abs value of it.

You also can get the string which formatted by Scientific Notation, by using toExponential/0. it doesn't accept any parameters.

> a.toExponential(100)
=> "1.000000e+02"
> a.toExponential()
=> "1.000000e+02"

Number operators

I think if you have learned JavaScript or any other programming language you will be familiar to +, -, *, /, etc. I think for explaining them, code will be better than my words.

> var a = 10
=> 10
> var b = 100
=> 100
> a + b
=> 110
> a - b
=> -90
> a * b
=> 1000
> a / b
=> 0.100000

Also support some bit operators.

> var a = 10
=> 10
> var b = 2
=> 2
> a | b
=> 10
> a & b
=> 2
> a % b
=> 0
> a ^ b
=> 0

Similar to javascript we also support ++, -- and something like (*)= which between two operands.

> var a = 10
=> 10
> a++
=> 10
> a
=> 11
> b = 11
=> 11
> --b
=> 10
> b
=> 10

# (*)= schema
> var a = 100
=> 100
> a += 10
=> 110
> a -= 10
=> 100
> a *= 10
=> 1000
> a /= 10
=> 100

> var a = 2
=> 2
> a |= 10
=> 10
> a = 2
=> 2
> a &= 10
=> 2
> a = 2
=> 2
> a %= 10
=> 2
> a = 2
=> 2
> a ^= 10
=> 8

Sorry about that I don't have enough time to talk about them one by one.

nil, true or false

Different to JavaScript we don't have too mush falsy. In Bean, We just have nil and false will be seen as false value. Others are truly.

> if (0) { print("I am true value") }
I am truly
=> nil
> if ("") { print("I am true value") }
I am truly
> if (true) { print("I am true value") }
I am true value
=> nil

=> nil
> if (false) { print("I am false value") }
=> nil
> if (nil) { print("I am false value") }
=> nil

Similar to Ruby, Just the false and nil are false value, the print branch with them will never run.

String

Basic

String must be a common data structure in modern programming language. When using Bean you can easy build a string literally.

> var a = "I am a string"
=> "I am a string"
> var b = "I am a string"
=> "I am a string"
> typeof a
=> "string"
> a == b
=> true

Easily, You can compare two strings by == operator. Otherwise you also can use the special method equal/1 to compare two strings.

> var a = "hello"
=> "hello"
> a.equal("hi")
=> false
> a.equal("hello")
=> true

The performance of == operator and equal/1 method is equivalent.

Bean also provide some common method to handle the string instance. If you want to transform the case of string, upcase/0, downcase/0, capitalize/0 are your choices.

> var a = "ruby is a Good programming language"
=> "ruby is a Good programming language"
> a.upcase()
=> "RUBY IS A GOOD PROGRAMMING LANGUAGE"
> a.downcase()
=> "ruby is a good programming language"
> a.capitalize()
=> "Ruby is a Good programming language"

What if you want to concat two string? You can use concat/1 method to do it.

> var a = "Bean"
=> "Bean"
> a.concat(" Ruby")
=> "Bean Ruby"
> a.concat(1)
Please pass a valid string instance as parameter.

As you can see. contact/1 just accepts string instance as parameter. If you want to concat others data type with a string, + operator may be a good choice.

> var a = "Bean"
=> "Bean"
> a + " 1"
=> "Bean 1"
> 1 + 1
=> 2
> "1 " + a
=> "1 Bean"

You can see that if one side of the + operator is a string instance, other side's instance will auto convert to string, and they will be contacted later.

In addition, We can use trim/0 method to clear the whitespace of the string both right side and left side.

>  "     Bean Language   ".trim()
=> "Bean Language"

slice and split

What should you do if you want to get slice of a sting? slice/2 can help you. That is a flexible method. It accepts 0~2 parameters.

if you don't pass any parameters, it will return the same string as target string.

> var a = "hello"
=> "hello"
> a.slice() == a
=> true

if you just pass one parameter, it will set the other one equals to the length of the string.

> var a = "hello world"
=> "hello world"
> a.slice(0)
=> "hello world"
> a.slice(1)
=> "ello world"
> a.slice(2)
=> "llo world"

It is obvious that what will happen if you pass two parameters.

> var a = "hello"
=> "hello"
> a.slice(0, 2)
=> "he"
> a.slice(3, 4)
=> "l"

Some tricks in slice/2 is that you can pass negative number as the index of the string. I will handle them by plus it with the length of the sting. You also use length attribute to get the string's length.

> var a = "hello world"
=> "hello world"
> a.slice(-3, -1)
=> "rld"
> a.slice(a.length - 3, a.length - 1)
=> "rl"
> a.slice(10, 4)
End index must greater than start index.

The last example will raise the exception, the end index must greater that start index.

The method similar to slice/2 is split/2. I will you some code, I think you will know what it can do.

> var a = "lan, zhi, heng"
=> "lan, zhi, heng"
> a.split(", ")
=> ["lan", "zhi", "heng"]
> a = "蓝，智，恒"
=> "蓝，智，恒"
> a.split("，")
=> ["蓝", "智", "恒"]

Split the string and store the result to an array.

UTF-8 Support

Bean not only supports the ASCII characters, also can handle the string which contain UTF-8 Characters. I will make some string contain Chinese, they will tell you the work of charAt/1, IndexOf/1, includes/1 and codePoint/0.

chartAt

> var a = "hello world"
=> "hello world"
> a.charAt(3)
=> "l"
> a = "你好，世界"
=> "你好，世界"
> a.charAt(2)
=> "，"

indexOf

> var a = "hello world"
=> "hello world"
>  a.indexOf(" ")
=> 5
> a = "你好，世界"
=> "你好，世界"
> a.indexOf("，")
=> 2

includes

> var a = "hello world"
=> "hello world"
> a.includes(" ")
=> true
> a = "你好，世界"
=> "你好，世界"
> a.includes("ha")
=> false

codePoint

> var a = 'hello'
=> "hello"
> a.codePoint()
=> 104
> a = 'h'
=> "h"
> a.codePoint()
=> 104
> a = "你好"
=> "你好"
> a.codePoint()
=> 20320
> a = "你"
=> "你"
> a.codePoint()
=> 20320

At last, I will show you the performance of length attribute and toNum method.

> var a = "hello world"
=> "hello world"
> a.length
=> 11
> a = "蓝智恒"
=> "蓝智恒"
> a.length
=> 3

As you can see, the length attribute will return the count of UTF-8 characters to you not just the count of bytes.

> var a = "hello"
=> "hello"
> a.toNum()
=> 0
> a = "212.333"
=> "212.333"
> a.toNum()
=> 212.333000

Finally, the toNum method is similar to Ruby's Number#to_i of Number#to_f methods. if the string can not convert to number they will return 0 to the caller.

Array

Basic methods

Let's talk about array data structure in Bean. As begining I will show you some basic method of array. They are pop/0, push/1, unshift/1, shift/0, join/1, reverse/0 and includes/1, respectively.

When you see the name of the method, you can guess what their work.

> var a = [1, "a", "b", true]
=> [1, "a", "b", true]
> a.pop()
=> true
> a
=> [1, "a", "b"]
> a.pop()
=> "b"
> a
=> [1, "a"]

As you can see, pop/0 method will pop the last item from the array. The fist one be poped is true value, the second is string "b".

push/1 method is opposite to pop/0, you can push items back like this.

> a
=> [1, "a"]
> a.push("b")
=> 3
> a.push(true)
=> 4
> a
=> [1, "a", "b", true]

Another thing you need to notice is when push successfully, it will return the size of current array.

shift/0 and unshift/1 are similar to pop/0 and push/1. The difference is that they handle the item at the head of the array, not tail.

> var a = [1, "a", "b", true]
=> [1, "a", "b", true]
> a.shift()
=> 1
> a.shift()
=> "a"

OK, at this case, the first item be "pop" is number 1, the second is string "a". Let's use unshift/1 to "push" back them.

> a
=> [1, "a"]
> a.unshift("a")
=> 3
> a.unshift(1)
=> 4
> a
=> [1, "a", "b", true]

Otherwise, you can reverse the array by using reverse/1 method.

> var a = [1, 2, 3, 4, 6]
=> [1, 2, 3, 4, 6]
> a.reverse()
=> [6, 4, 3, 2, 1]
> a
=> [6, 4, 3, 2, 1]

It will change the original order of the array, and return it back. And if you want to check if array contains the expect item, includes/1 is your choice.

> var a = [1, "lan", "ruby"]
=> [1, "lan", "ruby"]
> a.includes(false)
=> false
> a.includes("lan")
=> true

Almost, there are all the basic of array. Oh, leak one, the length attribute.

> a
=> [1, "a", "b", true]
> a.length
=> 4
> b = [1,2]
=> [1, 2]
> b.length
=> 2

Methods with callback

Bean also provides some functional methods which can accept callback. They are map/1, ``reduce/1, each/1`, `filter/1` and `find/1`.

The map/1 method accept a callback function as parameter, and then use this call back method to handle all items in array. Finally base of each return value from function's calling it will build a new array.

> var a= [1,2,3,4,5,6]
=> [1, 2, 3, 4, 5, 6]
> a.map(fn(x) { x * 2 })
=> [2, 4, 6, 8, 10, 12]
> a.map(fn(x, y) { x * y })
=> [0, 2, 6, 12, 20, 30]

You may notice two things. The first is that the keyword to define a function in Bean is fn. The second is that the first argument for the callback method is the item in array, the second is the index of the relevent item. This mechanism similar to JavaScript.

Next, Let's check each/1 method. it is similar to map/1, the difference is that it will not build a new array. it will return the original one. You can use it to finish some complex logic if you do not want to build a new array.

> var a = [1,2,3,4,5,6].reverse()
> a.each(fn(x, y) { print(y) })
0
1
2
3
4
5
=> [6, 5, 4, 3, 2, 1]
> a.each(fn(x, y) { print(x) })
6
5
4
3
2
1
=> [6, 5, 4, 3, 2, 1]

Next, Let's try to find item by find/1 with condition from the result of the callback. If you want to find item which greater than number 3 in the array, you can use this code.

> var a = [1,2,3,4,5,6]
=> [1, 2, 3, 4, 5, 6]
> a.find(fn (x, y) { x > 3 })
=> 4

But, find/1 method just can return only one item which match the condition. If you want to get all of them, please use filter/1.

> var a = [1,2,3,4,5,6]
=> [1, 2, 3, 4, 5, 6]
> a.filter(fn (x, y) { x > 3 })
=> [4, 5, 6]

That's all? No. we need to talk about the last one, reduce/1 method. it will accept two parameter, first is callback, second is the initial value of the flow. what flow? if you want to add from 1 to 10, you can do it by reduce/1.

> var a = [1,2,3,4,5,6,7,8,9,10]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> a.reduce(fn(a,b) { a + b }, 0)
=> 55
> a.reduce(fn(a,b) { print(b); a + b }, 0)
0
1
3
6
10
15
21
28
36
45
=> 55

You can see that the second parameter in callback will be the result of previous result of the callback. In the first round it will use the initial value.

No, You can simpily multiply from 1 to 10 by seting number 1 as the initial value.

> var a = [1,2,3,4,5,6,7,8,9,10]
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> a.reduce(fn(a,b) { a * b }, 1)
=> 3628800

Math

Math is a special hash object, of cause the simplest one. It just contains some method, have not ability to create some new instances.

There are the method list for Math, after that I will show you some demo.

• Math.ceil/1
• Math.floor/1
• Math.round/1
• Math.sin/1
• Math.cos/1
• Math.abs/1
• Math.sqrt/1
• Math.log/1
• Math.exp/1
• Math.random/1
• Math.min/1
• Math.max/1
• Math.pow/1

and also Math.PI equal to 3.14159265358979323846

There are some example for them.

> var a = 11.1
=> 11.100000
> Math.ceil(a)
=> 12

> var a = 11.9
=> 11.900000
> Math.floor(a)
=> 11

> var a = 1000.3333
=> 1000.333300
> Math.round(a)
=> 1000

> var a = 30
=> 30
> Math.sin(a * Math.PI / 180)
=> 0.500000
> Math.cos(a * 2 * Math.PI / 180)
=> 0.500000

> var a = -10000
=> -10000
> Math.abs(a)
=> 10000

> var a = 400
=> 400
> Math.sqrt(a)
=> 20

> var a = Math.exp(1)
=> 2.718282
> Math.log(a)
=> 1

> var a = Math.random()
=> 0.473279
> Math.round(Math.random() * 10 + 3)
=> 11

> a = 100
=> 100
> b = -100
=> -100
> Math.min(a,b)
=> -100
> Math.max(a,b)
=> 100
> Math.pow(a, 2)
=> 10000

OK, that all for Math library, so easy right?

Hash

Hash data structure in Bean, is similar to the Object in JavaScript. For simplicity, it is the only data structure can be inherited.

Hash is a key-value system. so sometime you want to get all the key of it. We can use keys/0 to get the result, the keys will be included in an array.

> var a = {name: "lanzhiheng", age: "xx"}
=> {name: "lanzhiheng", age: "xx"}
> a.keys()
=> ["name", "age"]

If you what to create a new Hash which can call the methods from current Hash, just using the clone/0 method.

> var a = { hi: fn() { print(self) }, sayHello: fn() { print("Hello") }}
=> {sayHello: [Function sayHello], hi: [Function hi]}
> var b = a.clone()
=> {}
> b.sayHello()
Hello
=> nil
> b.hi()
{}
=> nil

Date

1. Basic

In general, most of programming language will include the date-handling library. So I decide to add some simple feature to Bean.

If we want to get current timestamp we can use Date.now like this.

> Date.now()
=> 1583666189

Otherwise, we can make an instance by using Date.build, then we will have a batch of methods for this instance.

> var c = Date.build()
=> Sun Mar  8 19:26:59 2020
> c.getYear()
=> 2020
> c.getMonth()
=> 2
> c.getDate()
=> 8
> c.getHours()
=> 19
> c.getMinutes()
=> 26
> c.getSeconds()
=> 59
> c.getWeekDay()
=> 0

2. Parser

I provide a method named Date.parse to parse the time from time string. By default the formatter for parsing is %Y-%m-%d %H:%M:%S %z. So you can got the date instance like this

> var c = Date.parse("2020-3-30 10:30:00 +0800")
=> Mon Mar 30 10:30:00 2020

The time of printed string is equal to the params which in Date.parse method. Because I run this script in china, the timezone for my computer is Asia/Shanghai. If you wat to parse an UTC time. you can pass the parameter like this

> var c = Date.parse("2020-3-30 10:30:00 +0000")
=> Mon Mar 30 18:30:00 2020

Now, the parser think the string as UTC time. If you want to display it in Chinese timezone, it will become 18:30:00.

Also, you can define the formatter by your self. You can customize it by passing second parameter to Date.parse. Let't see the example, below.

> var c = Date.parse("10:30:00++++2020-3-30 +0000", "%H:%M:%S++++%Y-%m-%d %z")
=> Mon Mar 30 18:30:00 2020

OK, as you can see the result is right with the new formatter and new string which matched to it.

It should be noted that Date.now, Date.parse and Date.build methods just can invoke by the prototype Date. Don't use them in Date's instance.

3. Stringify

You can use instance method format to construct the Date string by the existing date instance. for example

> var f =  Date.parse("2020-3-30 10:30:00 +0000", "%Y-%m-%d %H:%M:%S %z")
=> Mon Mar 30 18:30:00 2020
> f.format()
=> "2020-03-30 18:30:00 +0800"

It is obvious that we parse the date string as the UTC time. If you format it later, you will get the result which tranformed by your current Timezone(Asia/Shanghai for me).

You also can specify the format string by passing a parameter to format method.

> f.format("%Y-%m-%d")
=> "2020-03-30"
> f.format("%H:%M:%S")
=> "18:30:00"

But the result of them will depended on your current Timezone. What should I do if I want to specify the timezone information when formatting the date instance? Just pass the timezone info as second parameter to format method.

> var h = Date.parse("2020-3-30 10:30:00 +0800", "%Y-%m-%d %H:%M:%S %z")
=> Mon Mar 30 10:30:00 2020
> h.format("%Y-%m-%d %H:%M:%S %z", "Asia/Shanghai")
=> "2020-03-30 10:30:00 +0800"
> h.format("%Y-%m-%d %H:%M:%S %z", "UTC")
=> "2020-03-30 02:30:00 +0000"
> h.format("%Y-%m-%d %H:%M:%S %z", "America/Toronto")
=> "2020-03-29 22:30:00 -0400"

The timezone which you pass to the method must match the tzfile names. If you pass an invalid timezone info, system will treat it as UTC.

> h.format("%Y-%m-%d %H:%M:%S %z", "UTC")
=> "2020-03-30 02:30:00 +0000"
> h.format("%Y-%m-%d %H:%M:%S %z", "Invalid")
=> "2020-03-30 02:30:00 +0000"

OK, I think that all about the date library for bean language. If I have some new idea, I will extend it.

Regular Expression

Simple demo

For using the regular expression feature in Bean, you should use Regex.build method to create the relative instance first.

> var regex = Regex.build('aa+')
=> /aa+/

After that, we can use instance's method to match something.

> regex
=> /aa+/
> regex.test('aaa')
=> true
> regex.test('AAA')
=> false

You also can choose your favor mode. For example, you can specify the ignore case mode like this, the result of test with the string "AAA" will become true

> var regex = Regex.build('aa+', 'i')
=> /aa+/
> regex.test('aaa')
=> true
> regex.test('AAA')
=> true

Syntax sugar for building

So simple, right? For convenience if you don't need to set the mode, you can build the regex expression by `` syntax sugar.

> `aaa+`
=> /aaa+/

Subexpression

Some time we want to handle subexpression in regular expression. we just need to involve the exec method, it will return an array to us.

> var c = Regex.build('(Hello) (Ruby)')
=> /(Hello) (Ruby)/
> c.exec("Hello Ruby, You are the best.")
=> ["Hello Ruby", "Hello", "Ruby"]

Otherwise, If the regular expression can not match any part of the string, we will get an empty array.

> var c = Regex.build('(Hello) (Ruby)')
=> /(Hello) (Ruby)/
> c.exec("Hello Python, You are the best.")
=> []

Shorthand Character Classes

Similar to javascript we can support the Shorthand Character Classes now. for example, \s for space characters, \w for a-z, A-Z, 0-9, _ characters and \d for 0-9 characters. You can define a regex expression like this. Also supported the opposite of them, \W, \D and \S.

> var c = Regex.build('\w+\s\d+\sRuby')
=> /\w+\s\d+\sRuby/
> c.test('Hello 1024 Ruby')
=> true

> var c = Regex.build('\D+\W\S+')
=> /\D+\W\S+/
> c.test('Hello Ruby')
=> true