GO / DATA AND COMPOSITION
Slices, maps, arrays, and memory sharing
Learn how slices, maps, arrays, and memory sharing works in Go, why the underlying model matters, and how to apply it in a small program without hiding important trade-offs.
What you will learn
- Explain slices in Go using the correct mental model
- Trace a focused Go example and predict its result before execution
- Recognize a boundary case involving maps and handle it deliberately
Understanding Slices, maps, arrays, and memory sharing
Slices, maps, arrays, and memory sharing belongs to the practical core of Go. Start by identifying the values or state involved and the rule that connects the input to the result.
Trace the example one operation at a time. Keep slices visible in the code rather than hiding it behind an abstraction before the behavior is understood.
Test a normal case and a boundary case. The difference between the prediction and the observed result is the most useful signal for deciding what to review next.
Slices, maps, arrays, and memory sharing is a defining part of practical Go work. Start by identifying the data or state involved, then trace the operation that changes or interprets it. Pay attention to the rules Go applies at this boundary, because those rules explain both the useful behavior and the common failure modes. This lesson keeps the example deliberately small, then connects it to strings, bytes, runes, and formatting so the ideas form a coherent progression rather than a list of isolated syntax facts.
Worked examples
Slices, maps, arrays, and memory sharing example
A focused Go example for slices.
package main
import "fmt"
func main() {
fmt.Println("Hello from Go")
}
// Lesson 9: slices. Change one value and predict the result before running it.Example explained
Line 1Identify where slices appears in the Go example and name the data it operates on.
Line 2Trace the relevant Go rule one operation at a time, recording any state, type, or control-flow change.
Line 3Change one input or boundary condition, predict the result, and compare that prediction with the documented outcome.
Important notes
Keep the first slices example small enough to trace completely.
Use the normal Go toolchain or browser workspace to compare the actual result with your prediction.
Common mistakes
Treating slices as punctuation to memorize instead of a Go behavior to reason about.
Ignoring maps until it appears in production data or a larger program.
Try it yourself
Change, predict, then run
Create a small Go example that demonstrates slices. Add a normal case and a boundary case, write down the expected result for each, then explain which Go rule produces that result. Lesson 9 should remain small enough to trace without guessing.
Open Go workspaceCheck your understanding
What is the best first step when working with slices?
- Identify the data and predict the result
- Add more abstraction immediately
- Ignore boundary cases
- Memorize punctuation only
Show answer
A clear input, operation, and predicted result create a testable mental model.