Learn Irij

A hands-on course in sixteen short lessons. Every example is a live editor and every exercise is checked as you go — nothing to install. Your progress stays in this browser.

Start with lesson 1

Foundations

  1. 1Hello, IrijYour first program: printing, strings, interpolation, and how arguments group.
  2. 2Values and bindingsIntegers that never overflow, exact fractions, strings, keywords — and names, mutable or not.
  3. 3FunctionsThree ways to write a body, currying, lambdas, and operators as values.
  4. 4Choosing and repeatingif, match with guards, cond and case, and recursion where other languages loop.
  5. 5CollectionsVectors, maps, sets, tuples and ranges: immutable, and cheap to update.
  6. 6PipelinesData flowing left to right: |>, map, filter, reduce and the other digraphs.
  7. 7Pattern matchingTake vectors, maps and tuples apart in bindings, arguments and match arms.

Modelling data

  1. 8SpecsSum and product specs, constructors, annotated fns, and checks at the boundary.
  2. 9ProtocolsOne name, many types: proto and impl.
  3. 10Errors and contractserror and try, Ok and Err, and pre/post conditions that know whom to blame.

Effects

  1. 11Effect rowsPure by default: what ::: Console means and how the compiler holds you to it.
  2. 12Effects and handlersDeclare an effect, give it meaning with a handler, swap the meaning freely.
  3. 13Handlers in practiceState, composition, aborting, on-failure — and testing effectful code.

Going further

  1. 14Concurrencyscope, fork and await on virtual threads; par, race and timeout.
  2. 15Modules and JavaThe standard library, qualified imports, and calling into the JVM.
  3. 16Capstone and next stepsPut it all together, then install Irij and build something real.