Lesson 3 / 27

Packages and main

Explain Packages and main, test a small program, and use the result to build confidence.

The essential idea

Packages and main becomes clear when you identify its job before memorising syntax. In Go, small explicit pieces combine into programs that are easy to read, build, and change.

See the Go path

Keep the path from source file to compiled program in mind as you learn this part.

Go source code moving through the go tool to a running program.
Figure 2.1 — A small Go idea fits into the build path.

A useful habit

Do not copy a solution blindly. For Packages and main, change one value, run go test or go run, and explain why the result changed.

Quick check

Quick check: How should you learn Packages and main?

  • Run one focused example and inspect the result.
  • Memorize it without writing code.
  • Skip compiler and test feedback.
Answer

Run one focused example and inspect the result. — Small experiments reveal cause and effect.