@rustable/iter

@rustable/iter

A TypeScript library providing Rust-style iterator adapters with a rich set of functional operations for collection manipulation.

Overview

@rustable/iter brings Rust's powerful iterator patterns to TypeScript, enabling functional, lazy, and composable operations on collections. It provides a rich set of iterator adapters that can be chained together to create complex data transformations with minimal overhead.

Features

• Lazy Evaluation - Computations are performed only when needed
• Chainable API - Fluent interface for composing operations
• Zero Dependencies - Lightweight and self-contained
• Type Safe - Full TypeScript support with strong type inference
• Rust-Inspired - Familiar API for Rust developers
• Tree-Shakeable - Only import what you need

Installation

npm install @rustable/iter

# or with yarn
yarn add @rustable/iter

# or with pnpm
pnpm add @rustable/iter

Usage

import { iter, range } from '@rustable/iter';

// Basic transformations
iter([1, 2, 3, 4, 5])
  .map((x) => x * 2)
  .filter((x) => x > 5)
  .collect(); // [6, 8, 10]

// Working with strings
iter('hello').enumerate().collect(); // [[0, 'h'], [1, 'e'], [2, 'l'], [3, 'l'], [4, 'o']]

// Numeric ranges
range(0, 5)
  .map((x) => x * x)
  .collect(); // [0, 1, 4, 9, 16]

API

Creation

• iter(iterable) - Create iterator from any iterable
• range(start, end, step?) - Create numeric range iterator

Transformation

• map(fn) - Transform each element
• filter(predicate) - Keep elements matching predicate
• flatMap(fn) - Map and flatten results
• flatten() - Flatten nested iterables

Subsetting

• take(n) - Take first n elements
• skip(n) - Skip first n elements
• stepBy(n) - Take every nth element
• takeWhile(predicate) - Take while predicate is true

Combining

• zip(other) - Combine with another iterator
• chain(other) - Append another iterator
• interleave(other) - Alternate elements with another iterator

Grouping

• groupBy(fn) - Group elements by key
• uniq() - Remove consecutive duplicates
• uniqBy(fn) - Remove duplicates by key

Terminal Operations

• collect() - Collect into array
• reduce(fn, initial?) - Reduce to single value
• forEach(fn) - Execute for each element
• find(predicate) - Find first matching element

Advanced Features

For more advanced iterator operations, you can import them from @rustable/iter/advanced:

import { iter } from '@rustable/iter';
import '@rustable/iter/advanced';

// Numeric operations
iter([1, 2, 3, 4]).sum(); // 10
iter([1, 2, 3, 4]).product(); // 24

// Comparison operations
iter([1, 4, 2, 3]).max(); // Some(4)
iter([1, 4, 2, 3]).min(); // Some(1)

// Partitioning
iter([1, 2, 3, 4, 5])
  .partition(x => x % 2 === 0); // [[2, 4], [1, 3, 5]]

// Chunking
iter([1, 2, 3, 4])
  .chunks(2); // [[1, 2], [3, 4]]

// Windows
iter([1, 2, 3, 4])
  .windows(2); // [[1, 2], [2, 3], [3, 4]]

// Scanning
iter([1, 2, 3])
  .scan(0, (sum, x) => sum + x); // [1, 3, 6]

// Grouping
iter([1, 1, 2, 3, 3])
  .groupBy(x => x); // [[1, [1, 1]], [2, [2]], [3, [3, 3]]]

These advanced features are separated to keep the core package lightweight. Import them only when needed.

Examples

Lazy Evaluation

const iter = iter([1, 2, 3, 4, 5])
  .map((x) => {
    console.log(`Processing ${x}`);
    return x * 2;
  })
  .filter((x) => x > 5);

// Nothing logged yet - no processing has occurred
const result = iter.collect(); // Now the processing happens

Complex Transformations

// Process user data
interface User {
  id: number;
  name: string;
  age: number;
}

const users: User[] = [
  /* ... */
];

iter(users)
  .filter((user) => user.age >= 18)
  .map((user) => ({
    id: user.id,
    displayName: user.name.toUpperCase(),
  }))
  .groupBy((user) => user.id)
  .collect();

// String processing
iter('Hello World!')
  .flatMap((s) => s.split(' '))
  .map((s) => s.toLowerCase())
  .filter((s) => s.length > 3)
  .collect(); // ['hello', 'world']

// Generate Fibonacci sequence
function* fibonacci() {
  let [a, b] = [0, 1];
  while (true) {
    yield a;
    [a, b] = [b, a + b];
  }
}

iter(fibonacci()).take(10).collect(); // [0, 1, 1, 2, 3, 5, 8, 13, 21, 34]

License

MIT Illuxiza