Kura is a statically typed , bytecode compiled scripting language written in C. It has hand written scanner , tokenizer , a custom made binary tree expression compiler and a stack based virtual machine.

• Overview

Kura source files are processed through four stage pipeline:

Source (.kura) -> Scanner -> Tokenizer -> Compiler -> Virtual Machine
ual Machine

The scanner produce raw lexemes , tokenizer classifies them , compiler convert them to bytecode chunks and the VM interprets that chunk on a value stack.

it iterate the raw source string character by character and cuts it into 'scanPtr' . each one holds starts pointer , end pointer , a byte length and a line number . It does not copy the source text which saves a lot of memory .It handles whitespace , string litrals , interget/float , alphabetic identifiers , single and double character signs , and comments (both single line and multi line).

It iterates the scanPtr array and classifies each span into a 'tokenType'.It classify scans in priority order:

1. Single character signs ('(' , ')', '{' , '}' , ';' , '=',...)
2. Two character signs ('==' , '!=' , '<=' , '>=', '&&' , '||' , '+=' , '-='), '+=' , '-=')
3. String litrals (spans surrounded by '"')
4. Integer/float numeric litrals
5. Data type keywords ('int' , 'float' , 'bool' , 'string')
6. General keywords ('if' , 'else' , 'while' , 'for', 'func' , 'return' , 'print' , 'break' , 'continue' , 'true' , 'false' , 'NULL' , 'exit')
7. Identifier (anything else)

Then these tokens are passed through 'functinize' , which seprates token streams into 'Tokens' which is a collection of tokens , each function has its own 'Tokens'.

Iterates Tokens of every function and output bytecode into 'Chunks' objects . it convert arithmetic expressions into a custom made binary expression tree , then the tree is traversed post order to produce stack machhine instructions. It track variable scopes with a trie based map. Functions are declared in a first pass so they can be forward called and compiled in a second pass.

Its a stack based virtual machine . It maintains:

• A value stack
• A call stack
• A variable arry

Variables should be declared with an explict type and should be assigned immediately.

int x = 45;
float y = 9.12;
bool flag = 1;
;

To updatet variables , we can use '=' , '+=' or '-=' operators:

x = x+1;
x += 10;
x -= 3;
;

Arithmetic

Comparision

Logical

Operator precedence : low -> highigh

|| -> && -> == , != , < , > , <= , >= -> + , - -> * , /
, >= -> + , - -> * , /

Functions should be declared with the 'func' keyword with their return data type , name and parameter list

func int add(int a , int b){
    return (a+b);
}
}

It supports 'if'/'else' , 'while' , and 'for' loops. We can also use 'break' and 'continue' to control loops. And 'return' to exits a function with a return value.e.

if(x==9){
    x=5;
}
else {
    x=10;
}
while(x<=10){
    print x;
    x-=1;
}

}
x-=1;
}

'print' is a built in statement that stdout only integers.

int x = 10 +5;
print x;

kura use two comment types:

# this is single line comment

// 
this is 
multi line 
comment
//


//

1. Cmake
2. C compiler
3. Make/Ninja

On Linux:

sudo apt install cmake gcc make

On macos:

brew install cmake
xcode-select --install

It compiles without debug outputs

cmake -S . -B build/release -DCMAKE_BUILD_TYPE=Release
cmake --build build/release

The binary is written to:

bin/Release/kura.exe

Run it:

linux:

bin/Release/Kura path/to/source/kura

windows:

./bin/Release/Kura.exe path/to/source.kura

This build defines the DEBUG macro, which enables diagnostic output.

cmake -S . -B build/debug -DCMAKE_BUILD_TYPE=Debug
cmake --build build/debug

the binary is written to:

bin/Debug/Kura.exe

Run it:

Linux:

bin/Debug/Kura path/to/source.kura

Windows:

./bin/Debug/Kura.exe path/to/source.kura

You can keep both files at same time and rebuild either one independently:

cmake --build build/release
cmake --build build/debug

./kura.exe path/to/code.kura

It reads the file , compiles it and execute it.

On success thee interpreter prints:

Complete!

Kura accepts any file path but '.kura' is recommended

This is still under development and There are many things which is not fully implemented.

1. Only int data types works
2. 'if'/'else' does not work right now
3. 'while'/'for' does not work right now

int a = 10;
int b = 3;

print a+b;
print a-b;
print a*b;
print a/b;
print a+b*2;
print (a+b)*2;
a+b)*2;

Run

./kura.exe arethmetic.kura

Output

13
7
30
3
16
26
Complete!
lete!

func int add(int a , int b){
    return a+b;
}

func int square(int n){
    return n*n;
}
func int hypotenuseSquare(int a , int b){
    return square(a)+ square(b);
}

print add(10 , 32);
print square(9);
print hypotenuseSquare(3,4);

quare(3,4);

Output

42
81
25
Complete!
e!

• Int data type
• Char data type
• float data type
• string data type
• vectors
• functions
• while loop
• for loop
• Expression evaluation
• Custom memory system (stack and heap memory)
• Comments
• Print
• Custom object definition
• Global variable