chore(docs): update README and docs

README.md

@@ -37,13 +37,26 @@ $ make install
 
 After installed, you can execute these commands below:
 
-```
+```bash
 melang -v //show version
 melang -h //help information
 melang a.mln b.mln ... //execute melang files
 ```
 
-**Example**
+
+
+### Docker Image
+
+If you need to quickly start a Melang runtime environment, you can use this Docker image.
+
+```bash
+docker pull melonc/melon
+```
+
+
+
+### **Example**
+
 ```
 //example.m
 
@@ -59,11 +72,13 @@ Hello World!
 ```
 
 
+
 ### Applications
 
 [Meproc](https://github.com/MelonCTech/Meproc): a cross-platform process management and supervision service.
 
 
+
 ### License
 
 [BSD-3-Clause License](https://github.com/Water-Melon/Melang/blob/master/LICENSE)

docs/coroutine.md

@@ -2,7 +2,7 @@
 
 Coroutine in Melang is time-sharing scheduled in a single thread.
 
-If you use the execution file which is generated by the repository on Github, script files in a same melang command will be executed in one process one thread.
+If you use the execution file which is generated by the repository on Github, script files in a same melang command will be executed in one process or even one thread.
 
 e.g.
 
@@ -13,15 +13,15 @@ $ ./melang a.mln b.mln ...
 
 
 
-Besides this way, there is a function named *eval* to start a new script task in the current thread to execute a piece of code.
+Besides this way, there is a function named `Eval` to start a new script task in the current thread to execute a piece of code.
 
 ```
 Eval(val, data, in_string, alias);
 ```
 
-If `in_string` is true, `val` is the script code, otherwise `val` is the script file path.
+If `in_string` is true, `val` will be the script code, otherwise `val` is the script file path.
 
-`data` will be passed to the new script task. If we want to use `data` in new task, we can use the variable named `EVAL_DATA` which is an internal variable added by `Eval`.
+`data` will be passed to the new script task. If we want to use `data` in new task, we can use the variable named `EVAL_DATA` which is a built-in variable added by `Eval`.
 
 `data` not support all data types, it just supports:
 
@@ -83,7 +83,7 @@ Here are two comprehensive examples of HTTP server. There are some functions whi
 
 
 
-There are two files: *server.mln* and *worker.mln*.
+There are two files: `server.mln` and `worker.mln`.
 
 Example 1.
 
@@ -116,7 +116,7 @@ net.tcp_close(fd);
 sys.print('quit');
 ```
 
-Now, you can use *ab (apache bench)* to test.
+Now, you can use `ab (apache bench)` to test.
 
 
 

docs/datatype.md

@@ -12,6 +12,7 @@ But every value has its type. Types in Melang are shown below:
 - array
 - set
 - object
+- function
 
 
 
@@ -43,10 +44,30 @@ d = ['age': 18, 'name': 'Mr. M'];
 human {
   name;
   age;
+  @run () { // this is a method definition.
+    //...
+  }
 }
 
 //value of o is an object or instance of set human.
 o = $human;
+
+//access object properties
+o.name;
+o.age = 1;
+
+//accessing non-existent object properties
+o.gender // nil will be given
+o.phone_number = 123; // the value of the new property `phone_number` has been set to 123.
+
+//here is a function definition
+@foo()
+{
+  //...
+}
+
+// and here is a function call
+foo();
 ```
 
 
@@ -61,9 +82,9 @@ a = [1, 2, 3];
 a[0]; //array[index]
 ```
 
-*a[0]* is getting the first element *1* in array *a*. And *a[2]* is the last element *3*.
+`a[0]` retrieves the first element `1` from the array `a`, while `a[2]` retrieves the last element `3`.
 
-If the index is greater than or equal to array length, *nil* will be got.
+If the index is greater than or equal to the array length, `nil` will be given.
 
 
 
@@ -73,10 +94,10 @@ There is another kind of array named *dict*.
 d = ['name': 'Tom', 'age': 18];
 ```
 
-Now if we want to access the element which *key* is *name*, we can do it in this way:
+Now if we want to access the element which *key* is `name`, we can do it in this way:
 
 ```
 d['name']; //dict[key]
 ```
 
-If *key* is not in this dict,  *nil* will be got.
+If *key* is not in this dict,  `nil` will be given.

docs/flowcontrol.md

@@ -31,24 +31,24 @@ if (conditions) {
 } fi
 ```
 
-*conditions* is one or more expressions.
+`conditions` is one or more expressions.
 
-The boolean value of *conditions* is not only including *true* and *false*, but also including any other values. So there are some values will be treated as *false*:
+The boolean value of `conditions` is not only including `true` and `false`, but also including any other values. So there are some values will be treated as `false`:
 
-- nil
-- 0
-- '' (null string)
-- [] (empty array)
+- `nil`
+- `0`
+- `''` (null string)
+- `[]` (empty array)
 
-In mode A: if conditions are satisfied (boolean value is *true*), interpreter will execute statements in *if* block.
+In mode A: if conditions are satisfied (boolean value is *true*), interpreter will execute statements in `if` block.
 
-In mode B: if conditions are satisfied, interpreter will execute statements in *if* block, otherwise *else* block statements will be executed.
+In mode B: if conditions are satisfied, interpreter will execute statements in `if` block, otherwise `else` block statements will be executed.
 
 > if there is only one statement in *if* or *else* block, the curly brackets around statement can be omitted.
 >
-> In mode B, the last *fi* can be omitted.
+> In mode B, there is no *fi* at the end of the statement block.
 
-There is a special case -- if - else if, e.g.
+There is a special case -- `if` - `else if`, e.g.
 
 ```
 if (a == 1)
@@ -58,7 +58,7 @@ else if (a == 10)
 fi
 ```
 
-Actually it just a combination of mode B and mode A. The last *if* statement is ONE statement, so we can omit curly brackets.
+Actually it just a combination of mode B and mode A. The last `if` is a single statement, so we can omit curly brackets.
 
 e.g.
 
@@ -124,11 +124,11 @@ for (expr1; expr2; expr3) {
 
 Interpreter will follow these steps to execute:
 
-1. execute *expr1* (expression).
-2. execute *expr2* and test its boolean value. if *true*, go to step3, otherwise go to step5.
-3. executed statements in *for* block.
-4. executed *expr3*, and go to step 2.
-5. *for* statement finished.
+1. execute `expr1` (expression).
+2. execute `expr2` and check its boolean value. if it is *truthy*, go to step3, otherwise go to step5.
+3. executed statements in `for` block.
+4. executed `expr3`, and go to step 2.
+5. `for` statement finished.
 
 > If there is only one statement in *for* block, the curly brackets around statement can be omitted.
 
@@ -154,13 +154,13 @@ while (conditions) {
 }
 ```
 
-*conditions* is one or more expressions.
+`conditions` is one or more expressions.
 
 Interpreter will follow these steps to execute:
 
-1. test *conditions*, if its boolean value is *true*, go to step 2, otherwise go to step 3.
-2. execute statements in *while* block and then go to step 1.
-3. *while* statement finished.
+1. test `conditions`, if its boolean value is `true`, go to step 2, otherwise go to step 3.
+2. execute statements in `while` block and then go to step 1.
+3. `while` statement finished.
 
 > If there is only one statement in *while* block, the curly brackets around statement can be omitted.
 
@@ -173,7 +173,7 @@ while (i < 10) {
 }
 ```
 
-#### 
+
 
 #### switch
 
@@ -193,10 +193,10 @@ switch (expr) {
 
 Interpreter will follow these steps:
 
-1. execute *expr* and record its value in interpreter.
-2. use *expr*'s value to match every case *value*. If matched (two values are same), go to step 3, otherwise go to step 2 to keep matching. If no case matched, and there is a *default* case in switch, the *default* will be matched, then go to step3. Otherwise go  to step 5.
+1. execute `expr` and record its value in interpreter.
+2. use `expr`'s value to match every case value. If matched (two values are same), go to step 3, otherwise go to step 2 to keep matching. If no case matched, and there is a `default` case in `switch`, the `default` will be matched, then go to step3. Otherwise go to step 5.
 3. executed statements those in matched case.
-4. keep executing next case statements but NOT to match case *value*. If there is any one case (including *default*) behind current one, go to step 4.
+4. keep executing next case statements but NOT to match case value. If there is any one case (including `default`) behind current one, go to step 4.
 5. *switch* statement finished.
 
 e.g.
@@ -215,7 +215,7 @@ switch (i) {
 }
 ```
 
-*break* statement which will be talked soon makes interpreter stop running in *switch*.
+`break` statement which will be talked soon makes interpreter stop running in `switch`.
 
 
 
@@ -227,12 +227,12 @@ Syntax:
 goto label;
 ```
 
-*goto* tells interpreter to go to a specified position marked by *label* and keep executing from the position.
+The `goto` statement tells the interpreter to jump to the specified position marked by the `label`, and continue execution from that position.
 
 e.g.
 
 ```
-sys = Import('sys');
+  sys = Import('sys');
 
   i = 10;
   goto plus;
@@ -242,9 +242,9 @@ plus:
   sys.print(i);
 ```
 
-*plus* is a label. The output of this code is 12 which means *i--;* is not executed.
+*plus* is a label. The output of this code is `12` which means `i--;` is not executed.
 
-> `goto` in Melang is a simplified.
+> `goto` in Melang is simplified.
 
 ```
 @foo()
@@ -262,7 +262,7 @@ l1:
 foo();
 ```
 
-The interpreter will throw an error that `l1` can not be found, because it is not in the outest statements in a function.
+The interpreter will throw an error that `l1` can not be found, because it is not in the outest statements in a function. The next example is working correctly.
 
 ```
 @foo()
@@ -280,13 +280,11 @@ li:
 foo();
 ```
 
-But this example is working correctlly.
-
 
 
 #### break
 
-*break* is a single statement. It is used to interrupt current loop (including *switch*), and jump out of the loop.
+`break` is a single statement. It is used to interrupt current loop (including `switch`), and jump out of the loop.
 
 e.g.
 
@@ -301,17 +299,17 @@ for (i = 0; i < 1000; i++) {
 sys.print(i);
 ```
 
-The output is 11, because when *i* greater than 10, *if* condition is matched. Then *break* statement makes *for* loop stop and go to execute next statement (*sys.print(i);*).
+The output is `11`, because when `i` greater than `10`, `if` condition is matched. Then `break` statement makes `for` loop stop and go to execute next statement (`sys.print(i);`).
 
 
 
 #### continue
 
-*continue* statement is also used in a loop (**except** *switch*).
+`continue` statement is also used in a loop (**except** `switch`).
 
-When interpreter encounter *continue* statement, the rest statements those behind *continue*, will not be executed, and go back to the beginnig of loop statements.
+When interpreter encounter `continue` statement, the rest statements those behind `continue`, will not be executed, and go back to the beginnig of loop statements.
 
-If *continue* is encountered in a  *for* loop, *expr3* and *expr2* will be executed and then back to the beginning of loop statements or finish loop (boolean value of *expr2* is *false*).
+If `continue` is encountered in a  `for` loop, `expr3` and `expr2` will be executed and then back to the beginning of loop statements or finish loop (boolean value of `expr2` is `false`).
 
 e.g.
 
@@ -333,11 +331,11 @@ Syntax:
 return value;
 ```
 
-Usually, return is used in a function. It will stop interpreter executing rest statement and return a value to the caller (outer scope).
+Usually, `return` is used in a function. It will stop interpreter executing rest statement and return a value to the caller (outer scope).
 
-*value* can be omitted, then the return value will be *nil*.
+`value` can be omitted, then the return value will be `nil`.
 
-If *return* appears in the outest scope, interpreter will stop execution, and this script task will be removed.
+If `return` appears in the outest scope, interpreter will stop execution, and this script task will be removed.
 
 e.g.