PART I
Warm-up
Reconnect with a useful idea before starting instructions and observable results. 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.
A rough note is enough. You can revise it after the example.
PART II
Instruction & guided example
Repair the operation rather than the example answer
Debugging begins with the promised behavior and a counterexample. If a helper named add returns a - b, changing only the chosen inputs until it happens to return the desired number conceals the error. Repair the operation responsible for the broken contract.
With a = 8 and b = 3, the broken expression a - b returns 5; the intended sum is 11. Replacing - with + gives 11. Check (8,0) afterward: both versions give 8, so this case cannot establish that the repair works. Then check (0,3): subtraction gives -3 and addition gives 3.
A passing zero case does not make the original implementation sound. The smallest useful repair changes one operator and retains a failing-case trace. Avoid hardcoding return 11: it passes only the first example and discards the meaning of the parameters.
Worked reasoning and supplied artifact
// Deliberately broken: the contract is addition.
fnc add(a: i32, b: i32) -> i32 {
return a - b;
}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
// Deliberately broken: the contract is addition.This comment explains intent for a reader. It is not an operation and should not be counted as an executed result.
fnc add(a: i32, b: i32) -> i32 {Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
return a - b;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
Write an expected/actual table for (8,3), (8,0) and (0,3), then repair the expression and retrace all three.
- 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.
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.
PART IV
Independent practice
Project context: Snack-shop calculator. Build a small, understandable change around instructions and observable results.
A gate-count helper promises addition but returns a * b. Repair it without hardcoding a result. Supply one case where multiplication accidentally agrees with addition and two where it fails.
What to produce
The one-operator repair, a failing-case explanation, and cases such as (2,2) → 4, (3,2) → 5, (0,4) → 4.
- 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.
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?
With a = 8 and b = 3, the broken expression a - b returns 5; the intended sum is 11. Replacing - with + gives 11. Check (8,0) afterward: both versions give 8, so this case cannot establish that the repair works. Then check (0,3): subtraction gives -3 and addition gives 3.
A passing zero case does not make the original implementation sound. The smallest useful repair changes one operator and retains a failing-case trace. Avoid hardcoding return 11: it passes only the first example and discards the meaning of the parameters.
Original learning-path task and reference
In a strategy simulation analytics tool, demonstrate instructions and observable results. 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 add(a: i32, b: i32) -> i32 {
return a + b;
}
fnc main() -> i32 {
return add(2, 3);
}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.
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 the operation rather than the example answer
- Debugging begins with the promised behavior and a counterexample. If a helper named add returns a - b, changing only the chosen inputs until it happens to return the desired number conceals the error. Repair the operation responsible for the broken contract.
- Separate source-backed behavior, host requirements and untested predictions.
One small recap task
Write one counterexample against a helper that always returns 11.
This marks your personal practice record only. It is not a certification or an official workspace assessment.