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4. Procedures

Level: beginner · Reading time: 3 min · Prerequisite: book/poche/03-conditions-and-loops.html · Last review: 2026-05-09

TL;DR (5 lines)

  • Read the core idea first.
  • Understand one concept at a time.
  • Run small examples.
  • Fix errors early.
  • Move to next chapter only when clear.

Frequent mistakes

  • Skipping prerequisites.
  • Reading without trying examples.
  • Fixing too many errors at once.

Prerequisites: book/poche/03-conditions-and-loops.html. See also: book/chapters/06-procedures.html.

Goal

Extract code into a reusable proc.

Example

proc add(a: int, b: int) -> int {
  give a + b
}

entry main at app/demo {
  return add(2, 3)
}

Why it matters

A procedure reduces duplication and makes code testable.

Quick check

What needs to be changed to add 3 numbers?

Try this

  1. Create mul(a, b).
  2. Call it from main.
  3. Compare results.

If you're stuck

A procedure = a clear objective + an explicit type of feedback.

Mini quiz

  1. What is the main goal of this chapter?
  2. Which concept is most important?
  3. What will you try right now?

See also

Next best action

Apply one idea from this chapter in a tiny example, then continue.