ASTWhile.java

public class ASTWhile implements ASTNode {
    ASTNode cond, body;

    public ASTWhile(ASTNode cond, ASTNode body) {
        this.cond = cond;
        this.body = body;
    }
    
    @Override
	public IValue eval(Environment<IValue> e) throws InterpreterError
    {
        while (true) {
            IValue condVal = cond.eval(e);
            if (condVal instanceof VBool) {
                if (!((VBool)condVal).getval()) {
                    return new VBool(false);
                }
                body.eval(e);
            } else {
                throw new InterpreterError("condition of while must be a boolean");
            }
        }
    }

    @Override
    public ASTType typecheck(Environment<ASTType> e) throws TypeCheckError, InterpreterError {
        ASTType condType = cond.typecheck(e);
        if (!(condType instanceof ASTTBool)) {
            throw new TypeCheckError("while: condition not bool");
        }
        body.typecheck(e);
        return ASTTBool.tbool;
    }

    @Override
    public boolean isFreeOutsideLambda(String id) {
        return cond.isFreeOutsideLambda(id) || body.isFreeOutsideLambda(id);
    }

}