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
Read a function signature as a promise
Read fnc as the start of a function declaration, then the name, parameters between parentheses, and the result type after ->. The body must explain how the promised result is obtained. Parameter names describe roles; their types describe the kinds of values accepted.
For offset(base: i32, change: i32) -> i32, offset(12,-3) binds base = 12 and change = -3. The body adds them and returns 9. The minus sign belongs to the supplied value, not to the helper’s chosen addition operator. The signature promises one i32 result; it does not promise a UI effect.
Confusing the function’s name with an argument or the result type changes how you read the whole declaration. i32 is not a second name for base and -> does not call another function. Match the body’s return expression back to the promised type and role.
Worked reasoning and supplied artifact
fnc offset(base: i32, change: i32) -> i32 {
return base + change;
}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 offset(base: i32, change: 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 + change;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
Mark declaration keyword, function name, each parameter name/type, and result type. Trace offset(12,-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.
Write and annotate a helper that combines existing stock with a signed adjustment. Trace (20,5) and (20,-5) and distinguish arithmetic from whether negative stock is allowed.
What to produce
An annotated typed helper, two traces returning 25 and 15, and a policy limitation.
- 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?
For offset(base: i32, change: i32) -> i32, offset(12,-3) binds base = 12 and change = -3. The body adds them and returns 9. The minus sign belongs to the supplied value, not to the helper’s chosen addition operator. The signature promises one i32 result; it does not promise a UI effect.
Confusing the function’s name with an argument or the result type changes how you read the whole declaration. i32 is not a second name for base and -> does not call another function. Match the body’s return expression back to the promised type and role.
Original learning-path task and reference
In a puzzle-level authoring tool, demonstrate reading a function from left to right. Read the source-grounded example and predict its observable behavior before making changes. 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.
- Read a function signature as a promise
- Read fnc as the start of a function declaration, then the name, parameters between parentheses, and the result type after ->. The body must explain how the promised result is obtained. Parameter names describe roles; their types describe the kinds of values accepted.
- Separate source-backed behavior, host requirements and untested predictions.
One small recap task
Say the offset signature aloud as an ordinary sentence.
This marks your personal practice record only. It is not a certification or an official workspace assessment.