merilang 3.0.0

Merilang — a desi-flavoured programming language with a full compiler front-end

Merilang 🇮🇳

A desi-flavoured programming language with a full compiler front-end — built in Python.

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What's New in v3.0 🆕

Merilang has graduated from a basic interpreter to a full compiler front-end:

Phase	What it does
🔍 Panic-mode Lexer	Collects all bad characters instead of stopping at the first one
🌳 Panic-mode Parser	Synchronises after errors and reports all syntax problems in one pass
🔬 Semantic Analyser	Static type-checking, scope resolution, arity checks — before any code runs
📐 IR Generator	Lowers the AST to Three-Address Code (3AC) viewable with --ir
🚀 Interpreter	Unchanged tree-walking execution on the verified AST

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Features ✨

• Desi Keywords — write code in Hindi-inspired syntax (maan, likho, kaam, …)
• Panic-mode Error Recovery — see every mistake in one run, not one at a time
• Static Semantic Analysis — undefined names, type mismatches and arity errors caught before execution
• IR Dump — inspect the generated Three-Address Code with --ir
• Full OOP — classes, inheritance, yeh (this), upar (super)
• Exception Handling — koshish / pakad / aakhir (try / catch / finally)
• Interactive REPL — persistent state across lines, --ir mode available
• Bilingual Errors — every error message in English and Hindi

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Installation 📦

From PyPI (recommended)

pip install merilang

From source

git clone https://github.com/XploitMonk0x01/merilang.git
cd merilang
pip install -e .

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Quick Start 🚀

Hello World

Create hello.meri:

maan naam = "Duniya"
likho("Namaste, " + naam + "!")

Run it:

merilang run hello.meri

Output:

Namaste, Duniya!

Interactive REPL

merilang repl

Merilang v3.0.0 Interactive REPL
>>> maan x = 10
>>> maan y = 32
>>> likho(x + y)
42
>>> niklo
Alvida! 👋

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Language Syntax 📝

Comments

// This is a comment

Variables

maan x = 42          // number
maan pi = 3.14       // float
maan naam = "Ravi"   // string
maan flag = sach     // boolean true
maan other = jhoot   // boolean false
maan nothing = khaali // null / None

Operators

Category	Operators
Arithmetic	+ - * / %
Comparison	== != > < >= <=
Logical	aur (and) ya (or) nahi (not)

Print & Input

likho("Hello!")                    // print with newline
likho_online("Enter name: ")       // print without newline
poocho naam "What is your name? "  // read input into 'naam'

Conditionals

maan umar = 20

agar umar >= 18 {
    likho("Adult")
} warna_agar umar >= 13 {
    likho("Teen")
} warna {
    likho("Child")
}

Loops

While loop:

maan i = 0
jab_tak i < 5 {
    likho(i)
    maan i = i + 1
}

For-each loop:

maan nums = [1, 2, 3, 4, 5]
har n mein nums {
    likho(n)
}

Break & Continue:

jab_tak sach {
    agar x > 10 { ruk }        // break
    agar x == 5 { age_badho }  // continue
    maan x = x + 1
}

Functions

kaam jodo(a, b) {
    wapas a + b
}

maan hasil = jodo(3, 4)
likho(hasil)   // 7

Lambda:

maan double = lambda(x) -> x * 2
likho(double(21))   // 42

Lists & Dicts

maan fruits = ["apple", "mango", "guava"]
likho(fruits[0])           // apple
likho(length(fruits))      // 3
append(fruits, "banana")

maan person = {"naam": "Raj", "umar": 25}
likho(person["naam"])      // Raj

Object-Oriented Programming

class Insaan {
    kaam __init__(naam, umar) {
        yeh.naam = naam
        yeh.umar = umar
    }

    kaam parichay() {
        likho("Mera naam " + yeh.naam + " hai.")
    }
}

class Chaatra extends Insaan {
    kaam __init__(naam, umar, school) {
        upar(naam, umar)
        yeh.school = school
    }

    kaam padhai() {
        likho(yeh.naam + " padh raha hai.")
    }
}

maan c = naya Chaatra("Aryan", 18, "IIT")
c.parichay()   // Mera naam Aryan hai.
c.padhai()     // Aryan padh raha hai.

Exception Handling

koshish {
    maan x = 10 / 0
} pakad galti {
    likho("Error: " + galti)
} aakhir {
    likho("Always runs.")
}

// Throw your own
kaam check_age(umar) {
    agar umar < 0 {
        uchalo "Umar negative nahi ho sakti!"
    }
    wapas sach
}

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CLI Reference 💻

# Run a script
merilang run script.meri

# Run with debug output (tokens + AST)
merilang run script.meri --debug

# Show Three-Address Code IR before running
merilang run script.meri --ir

# Skip semantic analysis (faster, less safe)
merilang run script.meri --no-semantic

# Interactive REPL
merilang repl
merilang repl --ir           # show IR for each line

# Show version
merilang version
merilang --version

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Built-in Functions 🔧

Function	Description
likho(...)	Print values
poocho(var, prompt)	Read user input
length(x)	Length of list or string
append(list, val)	Add element to list
pop(list, idx)	Remove & return element
insert(list, idx, val)	Insert at index
sort(list)	Return sorted copy
reverse(list)	Return reversed copy
sum(list)	Sum of elements
min(list) / max(list)	Minimum / Maximum
upper(s) / lower(s)	String case conversion
split(s, sep)	Split string → list
join(list, sep)	Join list → string
replace(s, old, new)	Replace in string
str(x) / int(x) / float(x)	Type conversion
bool(x) / type(x)	Type conversion / inspection
abs(x) / round(x, n)	Math helpers
range(n)	List [0 … n-1]

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Project Structure 🗂️

merilang/
├── merilang/
│   ├── __init__.py              # Public API (v3.0.0)
│   ├── __main__.py              # python -m merilang
│   ├── cli.py                   # Arg parsing + pipeline wiring
│   ├── errors_enhanced.py       # All error classes (bilingual)
│   ├── lexer_enhanced.py        # Phase 1 — tokeniser (panic-mode)
│   ├── ast_nodes_enhanced.py    # AST node dataclasses
│   ├── parser_enhanced.py       # Phase 2 — recursive-descent parser
│   ├── symbol_table.py          # Scope manager for semantic analysis
│   ├── semantic_analyzer.py     # Phase 3 — static analyser
│   ├── ir_nodes.py              # 3AC instruction dataclasses
│   ├── ir_generator.py          # Phase 4 — AST → IR lowering
│   ├── environment.py           # Runtime variable scoping
│   └── interpreter_enhanced.py  # Phase 5 — tree-walking interpreter
├── tests/
│   └── smoke_test_pipeline.py   # Full pipeline smoke tests
├── examples/                    # .meri example programs
├── Guide.md                     # In-depth developer guide
├── pyproject.toml               # PEP 517/518 packaging config
└── setup.py                     # Legacy build compat shim

Full developer reference: Guide.md

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Keyword Reference 🔤

Concept	Merilang	Python
Variable	maan x = …	x = …
Print	likho(…)	print(…)
Input	poocho var "prompt"	var = input("prompt")
If	agar … { }	if …:
Elif	warna_agar … { }	elif …:
Else	warna { }	else:
While	jab_tak … { }	while …:
For-each	har x mein list { }	for x in list:
Break	ruk	break
Continue	age_badho	continue
Function	kaam name(…) { }	def name(…):
Return	wapas …	return …
Lambda	lambda(x) -> expr	lambda x: expr
Class	class Name { }	class Name:
Inherit	class A extends B { }	class A(B):
New object	naya Name(…)	Name(…)
This	yeh	self
Super	upar(…)	super().__init__(…)
Try	koshish { }	try:
Catch	pakad e { }	except e:
Finally	aakhir { }	finally:
Throw	uchalo …	raise …
True / False	sach / jhoot	True / False
Null	khaali	None
Not	nahi	not
And / Or	aur / ya	and / or

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Error System 🚨

Merilang reports errors in English + Hindi with line/column positions. In v3.0 all errors from a single run are reported together (panic-mode), so you fix all issues at once.

[LexerError]  Line 4, Col 9: Unexpected character: '@'
[ParseError]  Line 8, Col 1: Expected expression, got 'EOF'
[SemanticError] Line 12: Undefined name 'resutl' — did you mean 'result'?
[TypeCheckError] Line 15: Cannot apply '-' to string and number

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Roadmap 🗺️

• Lexer + parser
• Tree-walking interpreter
• OOP (classes, inheritance)
• Exception handling
• Interactive REPL
• Panic-mode error recovery (v3.0)
• Semantic analysis pass (v3.0)
• IR / Three-Address Code generation (v3.0)
• Bytecode compiler & VM
• Standard library expansion
• VS Code extension
• Debugger with breakpoints
• Package manager

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Contributing 🤝

1. Fork the repo
2. Create a branch: git checkout -b feature/my-feature
3. Commit: git commit -m "Add my feature"
4. Push: git push origin feature/my-feature
5. Open a Pull Request

See Guide.md for a step-by-step walkthrough of how to add a new language feature.

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License 📄

MIT — see LICENSE.

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Made with ❤️ for the desi developer community