State changes with vary — Flash-check repair

PART I

Warm-up

Reconnect with a useful idea before starting state changes with vary. 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

Repair a replacement that should be an increment

Assignment and compound addition express different transitions. count = adjustment replaces the state with the adjustment itself. count += adjustment preserves the existing state and applies the change. Choose from the requirement rather than from how similar the operators look.

The broken stock helper starts at 12, then assigns stock = delivery where delivery is 5. It returns 5 and loses the existing 12. The intended stock after receiving a delivery is 12 + 5 = 17, so replace the assignment with +=. A before/after table makes the discarded value visible.

A zero initial stock would hide this defect because replacement and addition both produce the delivery amount. Keep a nonzero starting value as the regression case. Do not hardcode return 17; the helper should still work for other inputs.

Worked reasoning and supplied artifact

// Broken: delivery should be added to existing stock.
fnc receive(initial: i32, delivery: i32) -> i32 {
    vary stock: i32 = initial;
    stock = delivery;
    return stock;
}

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

// Broken: delivery should be added to existing stock.
This comment explains intent for a reader. It is not an operation and should not be counted as an executed result.
fnc receive(initial: i32, delivery: i32) -> i32 {
Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
vary stock: i32 = initial;
Introduce a binding intended to change. Identify its initial value now so later updates can be traced rather than guessed.
stock = delivery;
Read this statement in its surrounding contract. Identify which value or host operation it contributes; do not infer an undocumented API.
return stock;
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

Trace the broken and repaired helper for (12,5), then explain why (0,5) is insufficient alone.

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 state changes with vary.

Repair a points counter that starts at 20 but replaces points with a 4-point bonus. Add a second bonus afterward and record the expected sequence without hardcoded totals.

What to produce

A += repair and ledger 20 → 24 → 28, plus a zero-start masking explanation.

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 community library utility, demonstrate state changes with vary. Explain the flash answer, locate a plausible mistake, and repair the relevant part of your task. 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.

Why is receive(0,5) a weak sole repair test?Both replacement and addition produce 5Zero is not a valid integerThe helper cannot receive two parameters

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.

Repair a replacement that should be an increment
Assignment and compound addition express different transitions. count = adjustment replaces the state with the adjustment itself. count += adjustment preserves the existing state and applies the change. Choose from the requirement rather than from how similar the operators look.
Separate source-backed behavior, host requirements and untested predictions.

One small recap task

Give a nonzero-start counterexample against the broken replacement.

Your recap

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