Mutable and stable bindings — Change one requirement

PART I

Warm-up

Reconnect with a useful idea before starting mutable and stable bindings. In one or two sentences, describe the input, output or host boundary from the previous exercise that this lesson builds on. If you are arriving directly, skim the worked example first; there is no locked prerequisite.

Recall note

A rough note is enough. You can revise it after the example.

PART II

Instruction & guided example

Change which quantity is stable

A stable binding can name a setting for one calculation even if a different calculation uses another setting. Const does not mean every call everywhere must use the same literal; it means this binding’s role is stable within the shown example.

The example starts count at 4 and applies stable step 2 twice: 4 → 6 → 8. If the requirement changes to steps of 3, only the declaration of step changes: 4 → 7 → 10. This makes the repeated rule visible in one place instead of scattering matching literals through the body.

Changing only the first update to += 3 while leaving the second at += 2 implements mixed steps, not the revised rule. A named stable step avoids that partial edit. The mutable count and stable step still have different responsibilities after the requirement changes.

Worked reasoning and supplied artifact

fnc twoSteps() -> i32 {
    vary count: i32 = 4;
    const step: i32 = 2;
    count += step;
    count += step;
    return count;
}

Illustrative example from the proposed WillowScript design. The language and WUIX/WMATH/WDB/WAUDIO/WTMP services are not implemented in the supplied source. This site has no interpreter, VM or native host and does not execute or certify the snippet.

Walk through the example, one line at a time

fnc twoSteps() -> i32 {
Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
vary count: i32 = 4;
Introduce a binding intended to change. Identify its initial value now so later updates can be traced rather than guessed.
const step: i32 = 2;
Name a value that this example keeps stable. Inspect the right-hand side for the value or configuration being bound.
count += step;
Read the current value, add the right-hand amount and store the new value. A before/after trace makes the state change visible.
count += step;
Read the current value, add the right-hand amount and store the new value. A before/after trace makes the state change visible.
return count;
Evaluate the following expression using the current values, then send its result to the caller. Explain the value; do not confuse it with printed output.
}
Close the nested block or value begun earlier. Match it to its opening boundary to keep the structure readable.

Try the guided change

Change step to 3 and trace both updates. Explain why you did not change count to const.

Write the supplied inputs and initial state before following the example.
Reconstruct each intermediate calculation or host decision, then compare with the worked artifact.
Explain why the contrasting alternative fails before attempting the changed inputs in Part IV.

Prediction or guided notes

PART III

Take a breather

Step back after the guided example. Look away from the screen, stretch, or reread your prediction. This is an optional learning pause, not a timer or an assessment gate.

When you return, try to name the lesson’s key idea without copying its wording. If that feels difficult, return to Part II and trace one line rather than restarting the entire lesson.

Your drafts remain here. Continue whenever you are ready.

PART IV

Independent practice

Project context: Workshop stock counter. Build a small, understandable change around mutable and stable bindings.

A score counter starts at 10 and awards a stable 5 points for each of two completed tasks. Revise the rule to 7 points each. Show old/new traces and the single setting you changed.

What to produce

Two traces ending at 20 and 24 and a shared named reward binding used by both updates.

State the intended behavior in a sentence before editing.
Use only source-backed syntax and the host services whose contract you have been given.
Record a normal case and a boundary or unavailable-resource case.
Label hand predictions separately from anything actually measured in a supplied toolchain.

Your .ws practice draft

Syntax colors are a reading aid, not a compiler. The line you are editing stays uncolored until you move to a different line; capitalization is never changed. Drafts stay on this browser and code is not executed.

Need a hint?

Original learning-path task and reference

In a rhythm-game audio editor, demonstrate mutable and stable bindings. Adapt the task to a second host-neutral application context without changing the imported API contract. Include .ws source and a host-resource contract; compare at least one normal case and one edge case.

fnc total() -> i32 {
    vary count: i32 = 1;
    const bonus: i32 = 2;
    count += bonus;
    return count;
}

Where the original task needs a host API that is not supplied here, write the contract and predictions. Do not invent a runtime result.

PART V

Self-check

Use this check to notice what to revisit. It does not award a private course grade, block another page or claim to verify compiled code. Every answer has a learning explanation.

With count 4 and step 3 applied twice, what are the successive count values?4, 7, 104, 7, 94, 3, 3

Explain a normal or boundary case

You may keep exploring even if you are unsure. Use the hint, compare the trace, and revise your explanation.

PART VI

Recap & small task

Bring the idea back to the mod feature you are building. A useful recap connects the mechanism to a decision you can make in your own code.

Change which quantity is stable
A stable binding can name a setting for one calculation even if a different calculation uses another setting. Const does not mean every call everywhere must use the same literal; it means this binding’s role is stable within the shown example.
Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Explain what a shared step name protects against during an edit.

Your recap

This marks your personal practice record only. It is not a certification or an official workspace assessment.