Language basics

29 steps in 10 sets of Ruby.

Ruby was designed to make programmers happy, and you can feel it under your fingers: methods read like sentences, blocks turn loops into one-liners, and the punctuation budget goes to a few well-chosen sigils instead of ceremony. It powered the Rails wave that built Shopify, GitHub and Airbnb, and it remains one of the fastest languages to think in — what you mean and what you type are unusually close together.

This tour covers the language itself: strings and symbols, the core collections, control flow, and the blocks that make Enumerable the best iteration library anywhere. Then methods, classes, modules and the nil-safety idioms of daily Ruby, closing with files, exceptions and JSON. Every seed runs start to finish under Ruby 3.4 before it reaches you.

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Variables & strings

String interpolationVariables, strings, and the interpolation Ruby reaches for constantly.
String methodsThe everyday string toolkit: strip, split, sub and friends.
SymbolsWhy Ruby has two kinds of string and when the lightweight one wins.

Collections

ArraysBuilding, growing and querying Ruby's workhorse collection.
HashesKey-value pairs with defaults, fetch fallbacks and easy iteration.
RangesTwo dots or three: Ruby's ranges count, test, step and slice.

Control flow

Conditionalsif, elsif, unless and the one-line modifiers that read like prose.
case and whenPattern dispatch with ===: ranges, classes and regexps all match.
Loopstimes, upto, while and each — and why bare for loops are rare.

Blocks & iterators

each and mapThe two iterators that start every Ruby program.
select and detectFiltering a collection down to the elements you actually want.
reduceFolding a collection into one value, from sums to custom picks.

Enumerable

sort_by and group_byOrdering and bucketing with a key function instead of a comparator.
tally and slicesCounting and windowing built straight into Enumerable.
Enumerable queriesall?, any?, none? and count: questions a collection answers itself.

Methods & blocks

Method argumentsDefaults, keyword arguments and splats on ordinary methods.
yieldMethods that take a block and decide when to run it.
Procs and lambdasBlocks captured as objects you can store, pass and compose.

Classes & modules

Classes and attr_readerA minimal class: initialize, instance variables and readers.
Inheritance and superSubclassing with < and extending a parent method with super.
Modules and mixinsSharing behavior across classes without inheritance.

Nil & idioms

nil safetyThe operators that keep nil from taking down a call chain.
Multiple assignmentUnpacking arrays into variables, swaps, splats and nested pairs.
Struct and DataValue classes in one line, mutable or frozen.