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
Connect calculations through returned values
Two helpers compose when one returned value becomes an input to another. Keep this data route explicit. A caller waits for an inner call’s value before it can finish an outer call; it does not add the spelling of the helper names.
In main, add(125,75) first returns 200. The outer call is therefore add(200,25), which returns 225. Write the intermediate subtotal = 200 cents and final total = 225 cents. Only the final return leaves main; the subtotal is an intermediate value, not a second host result.
Flattening the trace to “125 + 75 + 25” can verify the arithmetic, but it hides the call boundaries you must understand when the helpers later implement different rules. Similarly, calling add twice in two separate returns would not combine the results; a return ends that function’s path.
Worked reasoning and supplied artifact
fnc add(a: i32, b: i32) -> i32 {
return a + b;
}
fnc main() -> i32 {
return add(add(125, 75), 25);
}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 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(add(125, 75), 25);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
Use a call tree with the inner call below the outer call. Replace the fee 25 with 0 and predict which intermediate row stays unchanged.
- 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.
Combine two workshop stock deliveries, 12 and 8, then add existing stock 5 through nested calls. Provide the call tree, every intermediate integer and the final host-visible prediction.
What to produce
A nested-call main, a tree showing 12 + 8 → 20 then 20 + 5 → 25, and the result unit.
- 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?
In main, add(125,75) first returns 200. The outer call is therefore add(200,25), which returns 225. Write the intermediate subtotal = 200 cents and final total = 225 cents. Only the final return leaves main; the subtotal is an intermediate value, not a second host result.
Flattening the trace to “125 + 75 + 25” can verify the arithmetic, but it hides the call boundaries you must understand when the helpers later implement different rules. Similarly, calling add twice in two separate returns would not combine the results; a return ends that function’s path.
Original learning-path task and reference
In a classroom scheduling assistant, demonstrate instructions and observable results. 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.
- Connect calculations through returned values
- Two helpers compose when one returned value becomes an input to another. Keep this data route explicit. A caller waits for an inner call’s value before it can finish an outer call; it does not add the spelling of the helper names.
- Separate source-backed behavior, host requirements and untested predictions.
One small recap task
If the fee changes, which helper definition needs editing in this design?
This marks your personal practice record only. It is not a certification or an official workspace assessment.