Appendix — Full Grammar (EBNF)

This appendix provides a complete grammar summary of EasyLang in a simplified EBNF-like notation.
It reflects how the interpreter parses code internally using its recursive-descent parser.

This is not a rigid compiler-formal grammar, but a clean, human-readable representation of the rules EasyLang follows.

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1. Program Structure

program = statement* ;

A program is a sequence of statements executed top-to-bottom.

---

2. Statements

statement = assignment
            | print_statement
            | if_statement
            | repeat_while
            | repeat_from
            | function_definition
            | return_statement
            | bring_statement
            | file_statement
            | break_statement
            | continue_statement
            | expression_statement ;

---

3. Assignment

assignment = "we let" IDENT "=" expression ;

Examples:

we let x = 10
we let name = "GreenBugX"

---

4. Printing

print_statement = "so print" expression ;

Example: so print x plus 1

---

5. Conditionals

if_statement = "if" expression "then" block
                ("else if" expression "then" block)*
                ("else" block)? ;

Example:

if x equals 10 then [
...
] else if x greater 20 then [
...
] else [
...
]

---

6. Loops

Repeat-While Loop

repeat_while = "repeat" "while" expression ":" "do" block ;

Repeat-From Loop

repeat_from = "repeat" "from" IDENT "=" expression
                "to" expression ":" "do" block ;

---

7. Functions

Function Definition

function_definition = "define" IDENT "(" arglist ")" ":" "do" block ;
arglist = (IDENT ("," IDENT)*)? ;

Example:

define add(a, b): do [
return a plus b
]

---

8. Return

return_statement = "return" expression ;

---

9. Bring (Module Import)

bring_statement = "bring" (STRING | IDENT) "as" IDENT ;

Examples:

bring "math.elangh" as math
bring math as m

---

10. File Operations

file_statement = file_open
                | file_writeline
                | file_readline
                | file_close ;

Open

file_open = "open" STRING "as" IDENT "for" ("read" | "write" | "append") ;

Write Line

file_writeline = "writeline" IDENT "with" expression ;

Read Line

file_readline = "readline" IDENT "into" IDENT ;

Close

file_close = "close" IDENT ;

---

11. Continue & Break

continue_statement = "continue" ;
break_statement = "break" ;

---

12. Blocks

block = "[" statement* "]" ;

Blocks create new scopes.

---

13. Expressions

EasyLang expressions follow a precedence hierarchy.

expression = logical_or ;

---

13.1 Logical OR

logical_or = logical_and ( "or" logical_and )* ;

---

13.2 Logical AND

logical_and = equality ( "and" equality )* ;

---

13.3 Equality

equality = comparison
            (("equals" | "not equals" | "==" | "!=") comparison)* ;

---

13.4 Comparison

comparison = term
            (("<" | ">" | "<=" | ">=" | "less" | "greater") term)* ;

---

13.5 Term (Addition / Subtraction)

term = factor
        (("plus" | "minus" | "+" | "-") factor)* ;

---

13.6 Factor (Multiplication / Division)

factor = unary
        (("mul" | "div" | "" | "/") unary) ;

---

13.7 Unary

unary = ("not") unary
        | call ;

---

13.8 Function Calls & Attribute Access

call = primary
        ( "(" argument_list? ")" # function_call
        | "." IDENT # attribute_access
        )* ;

argument_list = expression ("," expression)* ;

Examples:

math.sqrt(25)
user.name.upper()
list.push(5)

---

13.9 Primary Expressions

primary = NUMBER
            | STRING
            | "true"
            | "false"
            | IDENT
            | list_literal
            | dict_literal
            | "(" expression ")" ;

---

14. List Literals

list_literal = "[" (expression ("," expression)*)? "]" ;

Examples:

[1, 2, 3]
["a", "b", "c"]

---

15. Dictionary Literals

dict_literal = "{"
                (STRING ":" expression
                ("," STRING ":" expression)*
                )?
            "}" ;

Example:

{
"name": "GreenBugX",
"age": 16
}

---

16. Tokens (Lexical Layer)

IDENT = letter (letter | digit | "_")* ;
NUMBER = digit+ ("." digit+)? ;
STRING = '"' (anything except '"')* '"' ;
KEYWORDS = many reserved words ("we let", "if", "repeat", ...)

For details, see Lexical Structure.

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Summary

This appendix provides a full overview of the EasyLang grammar in EBNF form.
It summarizes:

• program structure
• all statement forms
• all expression types
• operator precedence
• function definitions and calls
• loops
• modules
• file operations
• literals
• lists and dictionaries
• full lexical details

Use this appendix as a quick reference when reading or writing EasyLang code, or when extending the interpreter itself.