Make names declared as constants immutable

[arsalan0c]

add #12

This is done by storing an additional variable (is_variable) which indicates whether a name was declared as a variable. When assigning a value to a name, the value of this variable is then checked. If it is true, (eg. for names declared with let), then the assignment is allowed. Otherwise, an error is thrown.

[arsalan0c]

We might need another way to automatically test this due to the inability to catch errors in Source

[anubh-v]

We might need another way to automatically test this due to the inability to catch errors in Source

We could add some data structure (at the global level) and use it to track errors. And then inspect it in the tests.

[arsalan0c]

We might need another way to automatically test this due to the inability to catch errors in Source

We could add some data structure (at the global level) and use it to track errors. And then inspect it in the tests.

Could you clarify how we could use a data structure to track errors?
As my understanding is that when testing it in Source, the test program will abort due to an error.

For example, if the following is a test then an error will be thrown due to constant reassignment.

parse_and_eval("const x = 2; x = 4; x;");

assert_equal(2, final_result);