CIO - Console Input/Output for Rust

CIO provides two powerful procedural macros (println! and input!) that bring Python-like convenience to Rust's type-safe environment. These macros streamline console interaction with advanced formatting and validation capabilities.

Installation

Add this to your Cargo.toml:

[dependencies]
cio = "0.4.0"

Features Overview

println! macro

• Python f-string style direct variable insertion ({var} instead of {} with separate arguments)
• ANSI color and style formatting with @(...) syntax
• Special formatters for data structures and collections (:a, :c, :j, :m, :d)
• Separator control with $(...) syntax to unify print! and println!
• Rich expression evaluation in format strings
• Pretty-print for all std::collections types with intuitive formatting

input! macro

• Type-safe input with automatic parsing and validation
• Error handling with colored error messages and re-prompting
• Support for multiple types (strings, numbers, booleans, chars)
• Validation of input length (especially for char inputs)

Examples

1. Basic Input and Output

use cio::{println, input};

// Type-safe input collection with validation
let name: String = input!("Your name: ");
let age: i32 = input!("Your age: ");
let height: f64 = input!("Your height (in meters): ");
let married: bool = input!("Are you married? (true/false): ");
let favorite_letter: char = input!("What is your favorite letter? ");

// Direct variable names in placeholders (Python f-string style)
println!("Hello, {name}, you are {age} years old!");

2. Colored and Styled Output

// Apply colors and styles with @(...) syntax
println!("@(green, bold)Success:@() Operation completed!");
println!("@(red, italic)Error:@() Something went wrong.");
println!("@(blue)Information:@() System is @(yellow)running@() normally.");

// Mix variables with styling
println!("@(bright_cyan, bold)User:@() {name} (@(bright_green){age}@() years old)");

3. Rich Expression Evaluation

// Direct expressions in format placeholders
println!("Age in months: {age * 12}");
println!("Height in cm: {height * 100.0:.0}");
println!("Name in uppercase: {name.to_uppercase()}");

// Conditional expressions
println!("Status: {if age >= 18 { "Adult" } else { "Minor" }}");

// Method calls
println!("First letter: {name.chars().next().unwrap_or('?')}");

4. Separator Control (Unifying print! and println!)

// No separator - works like println!
println!("Regular line with newline");

// With separator - works like print! with explicit separator
for i in 1..10 {
    println!("{i}$( - )");  // Prints "1 - 2 - 3 - ..." on one line
}

// Dynamic separators with variables
let separator = " | ";
println!("Item: {item}$(separator)");

5. Container Formatting

use std::collections::{HashMap, BTreeMap, VecDeque};

// Arrays and vectors
let numbers = vec![1, 2, 3, 4, 5];
println!("Numbers (array format): {numbers:a}");  // [1, 2, 3, 4, 5]

// Matrices
let matrix = vec![vec![1, 2, 3], vec![4, 5, 6], vec![7, 8, 9]];
println!("Matrix (standard format):\n{matrix:a}");  // Indented array
println!("Matrix (matrix format):\n{matrix:m}");    // With matrix borders
println!("Matrix (determinant format):\n{matrix:d}"); // With determinant bars

// HashMap
let mut capitals = HashMap::new();
capitals.insert("France", "Paris");
capitals.insert("Japan", "Tokyo");
println!("Capitals (pretty):\n{capitals:j}");  // JSON-like pretty format
println!("Capitals (compact): {capitals:c}");  // Single-line compact format

// Other collections
let queue = VecDeque::from([1, 2, 3, 4]);
println!("Queue: {queue:a}");  // Pretty prints any collection

6. Nested Structures

// Deeply nested data
let nested = vec![
    HashMap::from([
        ("name", "Alice"),
        ("scores", &[95, 87, 92])
    ]),
    HashMap::from([
        ("name", "Bob"),
        ("scores", &[78, 85, 90])
    ])
];

println!("Nested data (pretty):\n{nested:j}");

// 3D arrays
let cube = vec![
    vec![vec![1, 2], vec![3, 4]], 
    vec![vec![5, 6], vec![7, 8]]
];
println!("3D array:\n{cube:a}");  // Properly indented 3D structure

7. Input Validation

// String inputs (can't be empty)
let username: String = input!("Username: ");

// Numeric inputs (validates correct type)
let score: u32 = input!("Score (0-100): ");  // Rejects non-numbers or floats

// Boolean inputs (accepts various formats)
let proceed: bool = input!("Continue? (y/n): ");  // Accepts "true"/"false", "yes"/"no", "y"/"n", "1"/"0"

// Character inputs (ensures single character)
let grade: char = input!("Grade (A-F): ");  // Rejects multiple characters

8. Colored Input Prompts

// Styled input prompts
let name = input!("@(green, bold)Your name:@() ");
let age = input!("@(bright_cyan)Your age:@() ");

// Errors are automatically displayed in red with blinking
// Error: invalid digit found in string

Available Colors and Styles

Colors

• Basic: black, red, green, yellow, blue, magenta, cyan, white
• Bright: bright_black, bright_red, bright_green, bright_yellow, bright_blue, bright_magenta, bright_cyan, bright_white, gray (alias for bright_black)

Styles

• bold, italic, underline, dimmed, blink, reversed, hidden, strikethrough

Format Specifiers

• :a - Array format with proper indentation for nested structures
• :c - Compact single-line format for any data structure
• :j - JSON-like pretty format for complex structures
• :m - Matrix format with proper borders for 2D arrays
• :d - Determinant format with vertical bars

Key Benefits

• Python-like Simplicity: Familiar syntax for Python users with Rust's type safety
• Reduced Boilerplate: Eliminate repetitive input/output code patterns
• Visual Enhancement: Easily add colors and styles for better UX
• Data Visualization: Beautiful display of complex data structures
• Unified Interface: Consistent syntax for all output formatting needs
• Type Safety: Maintain Rust's safety guarantees with convenient syntax

How It Compares to Python

CIO combines the best of both worlds:

• Like Python's f-strings: Direct variable names in format strings ({var})
• Like Python's input(): Single-line input collection
• Beyond Python: Type validation, error handling, and rich formatting
• Rust Advantage: Maintains full type safety while offering convenience

License

This project is licensed under the MIT License.

CIO: Making console interaction in Rust as enjoyable as Python, but with the safety of Rust.