ASTId.java

public	class ASTId implements ASTNode	{	
    String id;	
    
    public ASTId(String id)	{
        this.id = id;
    }

    public String getId() {
        return id;
    }

    @Override
    public IValue eval(Environment<IValue> env) throws InterpreterError {
        IValue v = env.find(id);
        if (v instanceof VMut mut) {
            try {
                return ASTLet.mem.memrd(mut.getAddr()); 
            } catch (MemoryPanicError ex) {
                throw new InterpreterError("mut: " + ex.getMessage());
            }
        }
        return v;    
    }

    public IValue evalLValue(Environment<IValue> env) throws InterpreterError {
        return env.find(id);
    }

    // Rule Γ, x : mut(A) ⊢ x : A
    @Override
    public ASTType typecheck(Environment<ASTType> env) throws TypeCheckError, InterpreterError {
        ASTType t = env.find(id);
        if (t instanceof ASTTMut mut) {
            return ASTTypeDef.unfold(mut.getInner(), env);
        }
        return ASTTypeDef.unfold(t, env);
    }

    public ASTType typecheckLValue(Environment<ASTType> env) throws TypeCheckError, InterpreterError {
        return env.find(id);
    }

    @Override
    public boolean isFreeOutsideLambda(String id) {
        return this.id.equals(id);
    }

}