PART I
Warm-up
Reconnect with a useful idea before starting names, parameters, and return types. 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
Keep a result’s meaning through a helper boundary
A returned integer still has a feature meaning even though i32 alone does not encode it. When one helper’s output is passed onward, check both its type and its unit. A subtotal in cents can be added to a fee in cents; a count of items is not a substitute merely because it is also an integer.
cost(3,80) returns a subtotal of 240 cents. add(240,20) returns 260 cents. Passing add(3,20) instead would mix item count 3 with fee 20 cents and predict 23, a type-compatible but meaningless total. The trace should label the subtotal, not only its numeric value.
A green syntax color or matching i32 types cannot establish unit correctness. Carry the semantic contract beside the source, especially when composing helpers that all use the same numeric type.
Worked reasoning and supplied artifact
fnc cost(quantity: i32, unitPrice: i32) -> i32 {
return quantity * unitPrice;
}
fnc add(a: i32, b: i32) -> i32 {
return a + b;
}
fnc main() -> i32 {
return add(cost(3, 80), 20);
}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 cost(quantity: i32, unitPrice: i32) -> i32 {Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
return quantity * unitPrice;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.
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.
fnc main() -> i32 {Read the function name, its parameter names/types and the result type after ->. This is the contract the body must satisfy.
return add(cost(3, 80), 20);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
Label the inner return 240 cents and the outer fee argument 20 cents; then finish the call/return trace.
- 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 names, parameters, and return types.
Compose a helper for four tickets at 125 cents with a 30-cent fee. Show a correct route and a mistaken route that passes the ticket count directly to the fee addition.
What to produce
A correct result of 530 cents and a countertrace producing 34 with an explanation of its unit mismatch.
- 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?
cost(3,80) returns a subtotal of 240 cents. add(240,20) returns 260 cents. Passing add(3,20) instead would mix item count 3 with fee 20 cents and predict 23, a type-compatible but meaningless total. The trace should label the subtotal, not only its numeric value.
A green syntax color or matching i32 types cannot establish unit correctness. Carry the semantic contract beside the source, especially when composing helpers that all use the same numeric type.
Original learning-path task and reference
In a museum exhibit console, demonstrate names, parameters, and return types. Integrate this section with the preceding section’s artifact; identify inputs, outputs, and host capabilities. 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.
- Keep a result’s meaning through a helper boundary
- A returned integer still has a feature meaning even though i32 alone does not encode it. When one helper’s output is passed onward, check both its type and its unit. A subtotal in cents can be added to a fee in cents; a count of items is not a substitute merely because it is also an integer.
- Separate source-backed behavior, host requirements and untested predictions.
One small recap task
Name the semantic unit of cost’s return without quoting i32.
This marks your personal practice record only. It is not a certification or an official workspace assessment.