Explanation of Oslo error “M0197: ‘Text’ cannot be used in a Type context”?

Question

http://stackoverflow.com/questions/253666/explanation-of-oslo-error-m0197-text-cannot-be-used-in-a-type-context

Answer 1

In the M language values can be used as types, so when you write:

    type T {
        Text : Text;
        Other : Text;
    }

The binding of Other's type is to its sibling property named "Text". As you've noticed, in this case it is more a hinderance than a help. You can workaround this by using the fully qualified name for the text type of "Language.Text".

-josh

Answer 2

Hi Josh,

why is the same not holding in the case of user-defined types?

e.g.

module M {
    type X;
    type T {
      X : X;
      Y : X;
    }
}

Regards,
tamberg

Answer 3

The M compiler is reasonably relaxed about allow you to define empty types and not erroring until they become a problem.

If you give the type X a meaningful type you will see an error.

    type X : Integer32;
    type T {
        X : X;
        Y : X;
    }

This causes an error.

If however the type of the field X is a collection then it would be valid, if a bit wierd...

 

Answer 4

Thanks