writing-idiomatic-ruby

name	writing-idiomatic-ruby
description	Use when writing or reviewing Ruby — Enumerable-driven, expression-oriented idioms (blocks, guard clauses, safe navigation, keyword arguments, predicate methods) and the manual loops, nil checks, and temporary variables they replace.

Writing idiomatic Ruby

Idiomatic Ruby reads like intent. Lean on Enumerable and blocks, treat almost everything as an expression, and let objects answer questions about themselves.

Enumerable over manual loops

• map / select / reject / reduce / each_with_object instead of building an array with << inside a while/for. Use for essentially never.
• sum, min_by, max_by, group_by, partition, tally, flat_map — reach for the specific method before hand-rolling.
• each_with_object({}) or to_h to build hashes; filter_map to map-and-compact in one pass.

Expressions and flow

• Everything returns a value — assign from if/case, and let the last expression be the return (drop explicit return except for guard clauses).
• Guard clauses with trailing if/unless and early return/next over nested conditionals.
• case/when (and pattern matching case/in in 3.x) over long elsif chains.
• Prefer &&/||, ||=, and the safe-navigation &. over verbose nil checks.

Objects and methods

• Predicate methods end in ? and return booleans; bang methods (!) mutate or raise.
• Keyword arguments for clarity when a method takes more than one or two options; avoid boolean positional flags.
• attr_reader/attr_accessor over hand-written accessors. Symbols for identifiers/keys.
• tap for side effects in a chain; then/yield_self to pipe a value through a transform.

Hygiene

• # frozen_string_literal: true at the top of files.
• Two-space indentation; do…end for multiline blocks, {…} for one-liners.
• Don't rescue Exception — rescue StandardError (the default) or a specific class.

Run RuboCop for formatting and lint — this skill is about the idioms above, not whitespace. American English in identifiers and comments.