PART I
Warm-up
Reconnect with a useful idea before starting reading a function from left to right. 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
Revise a body while preserving the calling contract
A caller depends on a helper’s name, parameter order and result type. A rule can sometimes change inside the body while those surface details remain stable. Review both the old and new behavior instead of assuming a stable signature means stable semantics.
The original bonus(base,extra) returns base + extra. The new event rule awards two extras, so its body becomes base + extra * 2. At (10,3), the old result is 13 and the new result 16. The call still supplies two i32 values in the same order and receives an i32, but its meaning has changed.
A type-compatible change can still break a user’s expectation. Document the new rule and retrace known calls. Conversely, renaming a parameter consistently inside a helper usually changes readability rather than the arithmetic; distinguish the two kinds of edit.
Worked reasoning and supplied artifact
fnc bonus(base: i32, extra: i32) -> i32 {
return base + extra;
}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 bonus(base: i32, extra: i32) -> i32 {Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
return base + extra;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 only the body to double extra and create an old/new result table for (10,3) and (0,3).
- 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 reading a function from left to right.
A crafting helper currently returns base + gift. A promotion adds three gifts. Preserve its signature, revise its expression, and demonstrate one old call whose returned value changes and one whose value stays unchanged.
What to produce
A stable signature, a revised body and cases with nonzero gift versus gift zero.
- 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?
The original bonus(base,extra) returns base + extra. The new event rule awards two extras, so its body becomes base + extra * 2. At (10,3), the old result is 13 and the new result 16. The call still supplies two i32 values in the same order and receives an i32, but its meaning has changed.
A type-compatible change can still break a user’s expectation. Document the new rule and retrace known calls. Conversely, renaming a parameter consistently inside a helper usually changes readability rather than the arithmetic; distinguish the two kinds of edit.
Original learning-path task and reference
In a strategy simulation analytics tool, demonstrate reading a function from left to right. 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 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.
- Revise a body while preserving the calling contract
- A caller depends on a helper’s name, parameter order and result type. A rule can sometimes change inside the body while those surface details remain stable. Review both the old and new behavior instead of assuming a stable signature means stable semantics.
- Separate source-backed behavior, host requirements and untested predictions.
One small recap task
Name one caller expectation you would document before changing the body.
This marks your personal practice record only. It is not a certification or an official workspace assessment.