Functional Programming Best Practices

Quick Start

-- Prefer pure functions and immutable data
let double = (x) -> x * 2
[1, 2, 3] /> map(double) /> filter((x) -> x > 2)

Core Principles

• Immutability: Use let by default, maybe only when mutation is necessary
• Pure functions: No side effects, same input always produces same output
• Composition: Build complex behavior from simple, composable functions
• Higher-order functions: Pass functions as arguments, return functions

Lea-Specific Warnings

Lea differs from traditional FP languages:

• No currying - Use placeholders: 5 /> add(3, input)
• Pipes prepend - x /> fn(a) becomes fn(x, a)
• Mutable bindings - maybe allows mutation; avoid unless necessary
• No monads - Async uses #async decorator instead
• Opt-in types - Add :: Type :> ReturnType, use #strict for enforcement

Notes

• Prefer let over maybe
• Use pipelines (/>) for left-to-right data flow
• Callbacks receive (element, index)