DEV Community: Callebe Josué Cantú

Estou criando minha própria linguagem de programação em Python

Callebe Josué Cantú — Thu, 04 Jun 2026 22:16:35 +0000

Há algum tempo comecei um projeto chamado Exper.

A ideia era simples: aprender mais sobre interpretadores e design de linguagens criando minha própria linguagem de programação.

No início ela era extremamente simples, mas aos poucos foi ganhando recursos como:

Variáveis
Funções
Structs
Loops
Condicionais
Listas
Interpolação de strings

Hoje a Exper já consegue executar programas relativamente grandes.

O que mais tem me ajudado no desenvolvimento não são exemplos pequenos, mas sim um RPG de texto que estou criando para testar a linguagem.

Esse RPG força a implementação de recursos reais:

Inventário
Objetos
Combate
Estruturas de dados
Passagem por referência
Manipulação de listas

Curiosamente, a maior parte dos bugs aparece apenas quando tentamos construir algo real.

Por exemplo, recentemente descobri problemas relacionados a passagem por referência e mutabilidade ao implementar um sistema de inventário para poções.

Esse tipo de problema dificilmente apareceria em exemplos simples de calculadora.

Exemplo da linguagem

struct Player {
    name,
    hp = 100
}

player = Player()
player.name = "Callebe"

console.log("{player.name} possui {player.hp} HP")

O que aprendi até agora

Criar uma linguagem é muito mais difícil do que parece.

Quando você acredita que terminou:

Surge um problema de escopo.
Depois um problema de mutabilidade.
Depois um problema de parsing.
Depois um problema de listas.
Depois um problema de referências.

Mas é justamente isso que torna o projeto interessante.

Próximos passos

Melhorar suporte a métodos
Operadores compostos
Sistema de módulos
Classes
Exceções

O objetivo não é criar um concorrente para Python ou JavaScript.

O objetivo é aprender como essas linguagens funcionam internamente.

E, até agora, a Exper tem sido uma excelente professora.

Código completo aqui

I built my own programming language in Python (Exper Language)

Callebe Josué Cantú — Fri, 29 May 2026 14:12:49 +0000

🧠 Introduction

I’ve been building my own programming language called Exper, written from scratch in Python.

The goal is to understand how interpreters work internally and experiment with language design (functions, loops, expressions, and control flow).

Right now, Exper is already a working mini-language capable of executing real programs.

⚙️ What Exper can do so far

The language already supports:

Variables
Functions (with default and named parameters)
If / elif / else conditionals
While and for loops
Return, break and continue
String interpolation using {expression}
Lists and basic methods (append, pop, remove, insert)
Console input/output
Expression evaluation (including function calls inside expressions)

💻 Example code in Exper

fn soma(a, b=10) {
    return a + b
}

console.log(soma(5))
console.log(soma(5, 20))
console.log(soma(a=7, b=3))

nome = "Callebe"
idade = 12

if (idade > 17) {
    console.log("{nome} is an adult.")
} else {
    console.log("{nome} is not an adult.")
}

⚙️ How it works

Exper is interpreted using a custom Python engine that:

Parses line-by-line execution
Evaluates expressions using a safe evaluator
Handles function calls with local scope simulation
Supports nested expression evaluation
Implements control flow using exceptions (break/continue/return)

⚠️ Current challenges

This project is still evolving. Some known challenges:

Expression evaluation still relies partially on eval
Function parsing and argument handling is improving
Scope system is currently simulated (not fully isolated)
Error messages are basic and need improvement
String interpolation and edge cases still being refined

🚀 What I want to improve next

Better parser (possibly AST-based instead of eval)
Real scope system (local/global separation)
Better error handling system
More operators (like XOR, increment, assignment operators)
Structs / objects / macro-like features
Standard library system

📌 Final note

This started as a small experiment and turned into a full mini interpreter.
I’m learning a lot about how programming languages actually work under the hood.

Any feedback on interpreter design, architecture or performance improvements is welcome.

full source code here

I built my own programming language in Python (Exper Language)

Callebe Josué Cantú — Fri, 29 May 2026 14:12:49 +0000

A while ago, I started a project called Exper.

The idea was simple: learn more about interpreters and language design by building my own programming language.

At first, it was extremely simple. Over time, it gained features such as:

Variables
Functions
Structs
Loops
Conditionals
Lists
String interpolation

Today, Exper can already run relatively large programs.

What has helped me the most is not small examples, but a text-based RPG that I am building to test the language.

The RPG forces the implementation of real-world features:

Inventory systems
Objects
Combat mechanics
Data structures
Reference passing
List manipulation

Interestingly, most bugs only appear when you try to build something real.

For example, I recently discovered several issues involving reference passing and mutability while implementing an inventory system for potions.

Those problems would probably never appear in simple calculator examples.

Example

struct Player {
    name,
    hp = 100
}

player = Player()
player.name = "Callebe"

console.log("{player.name} has {player.hp} HP")

What I've Learned

Building a programming language is much harder than it seems.

Every time you think you're done:

A scope bug appears.
Then a mutability bug.
Then a parser bug.
Then a list bug.
Then a reference bug.

But that's exactly what makes the project interesting.

What's Next

Better method support
Compound operators
Module system
Classes
Exceptions

The goal is not to compete with Python or JavaScript.

The goal is to understand how they work internally.

So far, Exper has been an amazing teacher.

full source code here