Semantic Analysis

Implement semantic analysis for the expanded language (v2).

You are given a parsed Program AST. Your job is to check scoping and rule violations, returning a list of error messages.

Function signature

func Analyze(prog *Program) []string

Return a slice of error strings. If there are no errors, return an empty slice.

Rules to enforce

1. No duplicate declarations in the same scope:

redeclare in same scope: <name>

2. Names must be declared before use:

undefined name: <name>

3. Const rules:

• const must have an initializer

const requires initializer: <name>

• assignment to const is not allowed

cannot assign to const: <name>

4. Return placement:

• return is only valid inside a function

return outside function

5. Function calls:

• Calling a non-function name is an error

call of non-function: <name>

• Arity must match the declared function parameter count

arity mismatch: <name> expects <n>

Notes

• The language is dynamically typed; do not type-check expressions.
• Functions are top-level declarations, but the analyzer should still behave sensibly if they appear elsewhere.
• Errors should be reported in the order encountered during a left-to-right traversal.

Before implementation

Use the module’s worked reconstruction and independent debugging lab to predict an intermediate artifact first. Preserve one failing counterexample while implementing the stated API. The lesson’s transfer task uses a fresh case after the guided trace.