# NEK-Lang

## High level Components

- [x] Lexer: Transforms text into Tokens
- [x] Parser: Transforms Tokens into Abstract Syntax Tree
- [x] Interpreter (tree-walk-interpreter): Walks the tree and evaluates the expressions / statements
- [ ] Abstract Syntax Tree Optimizer

## Language features

- [x] Math expressions
  - [x] Unary operators
    - [x] Negate `-X`
  - [x] Parentheses `(X+Y)*Z`
  - [x] Logical boolean operators
- [x] Variables
  - [x] Declaration
  - [x] Assignment
- [x] While loop `while X { ... }`
- [x] If else statement `if X { ... } else { ... }`
  - [x] If Statement
  - [x] Else statement
- [ ] Line comments `//`
- [x] Strings
- [x] For loops `for X; Y; Z { ... }`
- [ ] IO Intrinsics
  - [x] Print
  - [ ] ReadLine

## Grammar
### Expressions
```
LITERAL = I64 | Str
expr_primary = LITERAL | IDENT | "(" expr ")" | "-" expr_primary
expr_mul = expr_primary (("*" | "/" | "%") expr_primary)*
expr_add = expr_mul (("+" | "-") expr_mul)*
expr_shift = expr_add ((">>" | "<<") expr_add)*
expr_rel = expr_shift ((">" | ">=" | "<" | "<=") expr_shift)*
expr_equ = expr_rel (("==" | "!=") expr_rel)*
expr_band = expr_equ ("&" expr_equ)*
expr_bxor = expr_band ("^" expr_band)*
expr_bor = expr_bxor ("|" expr_bxor)*
expr = expr_bor
```

## Statements
```
stmt_expr = expr
stmt_let = "let" IDENT "=" expr
stmt_while = "while" expr "{" (stmt)* "}"
stmt_for = "for" stmt_let ";" expr ";" expr "{" (stmt)* "}"
stmt_if = "if" expr "{" (stmt)* "}" ( "else" "{" (stmt)* "}" )
stmt_dbgprint = "$$" expr
stmt_print = "$" expr
stmt = stmt_expr | stmt_let | stmt_while | stmt_for | stmt_if | stmt_dbgprint | stmt_print
```