cypher-lang

cypher-lang is dynamically typed interpreted language written in rust. cypher lang compiles down to cypher bytecode interpreted by cypher virtual machine.

cypher syntax

Data Types

let boolean = false or true
let strings = "hello world!"
let numbers = 555
let arrays = [1,2,3,4]

control flow

if Statements

let i=5
if  i%2==0{
   print("even")
}else{
   print("odd")
}

while loop

let n=0
while n<=10{
   print(n)
   n++
}

Functions

def fact(num){
   let res=1
   let i=1
   while i<num{
      res=res*i
      i++
   }
   return res
}

let hello=def (){
   print("hello world!")
}

hello()
let a=fact(5) 

Builtins

len() function

let a=len("hello") //returns length of string
let b=len([1,2,3]) //returns length of array

push function

let a=[1,2,3,4]
push(a,5)

cypher grammar

program        → declaration* EOF ;
declaration    → varDecl
               | statement ;
while ->  "while" <expression> "{" <statement>* "}"
varDecl        → IDENTIFIER ( "=" expression )? ";" ;
statement      → <exprStmt>
               | <printStmt>
                  <ifStatement>;
ifStatement → "if" <expression> "{" <statement>  (else <statement>)? "}" ;
exprStmt       → <expression> ;
printStmt      → "print" <expression> ;
expression     → ('[' (<expression>)* ']') | <assignment> ;
assignment     → ( call "." )? IDENTIFIER "=" assignment
               | logic_or ;
logic_or       → logic_and ( "or" logic_and )* ;
logic_and      → equality ( "and" equality )* ;
equality       → <comparison> ( ( "!=" | "==" ) <comparison> )* ;
comparison     → <term> ( ( ">" | ">=" | "<" | "<=" ) <term> )* ;
term           → <factor> ( ( "-" | "+" ) <factor> )* ;
factor         → <unary> ( ( "%" | "/" | "*" ) <unary> )* ;
unary          → ( "!" | "-" ) <unary>
               | <primary> ;
increment      → <call> ( "++" | "--")
array index   -> identifier ('[' <expression> ']') | <call>
call           → <primary> ( "(" arguments? ")" | "." IDENTIFIER )* ;
primary        → NUMBER | STRING | "true" | "false" | "nil"|identifier
               | "(" <expression> ")" ;

cypher bytecode

opcode	operands	description
LC	1	Load constant
ADD	2	Addition Operator
SUB	2	Subtraction Operator
MUL	2	Multiplication Operator
DIV	2	Division Operator
MOD	2	Modulo Operator
PRINT	0	Call Print Function
CALL	1	Call operator
LT	2	Less than Operator
GT	2	Greater than Operator
GOE	2	Greater than Equal Operator
LOE	2	Less than Equal Operator
JMP	1	Jump
JNE	1	Jump not equal
Get Global	1	get global variable
NOP		No Operation

source

let a=3

if a<5{
    print("less")
}else{
    print("greater")
}

generated bytecode

examples/hello.cy:
      lc     3
      get    3
      lc     5
      le
      jne    14
      lc     less
      print
      jmp    17
      lc     greater
      print

Todo

• lexer
• parser
• symbol table
• global variables
• bytecode generator
• local scopes
• functions and function calls
• implement vm
• implement modules
• implement std