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.