klodolph • today at 3:59 AM

> I do not see why we need to make any design decision to specify object layout

> we simply need a code pointer and static chain pair

The code pointer and chain pair needs an object layout. You would have to pick a specific layout, and it would not be compatible with other languages that have a different layout.

Right now I can do this:

    struct a {
      void (*fun)(void *ctx);
      int data1;
      int data2;
    };
    struct b {
      void (*fun)(void *ctx);
      void *ctx;
    };

And I could call them:

     struct a *aptr;
     a->fun(aptr);

     struct b *bptr;
     b->fun(bptr->ctx);

There is only one neutral, maximally compatible option here—which is to have the function pointer separate from the arguments you want to pass in, and pass them in explicitly.

If you add closures to C you are making compatibility worse, not better.