abstraction boundaries

[amitu]

Read this interesting idea:

things lower down in the hierarchy are not allowed to call back into things higher up in the hierarchy

This is how I translate this in my head: should ftd.* functions be able to call design-system.* functions? No. Should design-system.* be able to call into fifthtry.ftd (fifthtry website built using design-system)? Again, of course no.

Now these no-s get enforced because ftd rust code does not have access to design-system.*, nor design-system.* have access to fifthtry.* in the first place.

But if you are working on larger projects, we tend to put everything in one big package, and things get dump, and obstructions at lower level technically has access to abstractions at higher level.

We can enforce this by breaking things into packages. But within the same package there are no abstraction boundaries, there is no concept of "hierarchy".

Should we have some such syntax? Like say letting a module labelled with some sort of hierarchy number, eg fifthtry/lib.ftd may have lower hierarchy number than rest of the fifthtry/*, so the calls, imports are only allowed from higher to lower, and never lower to higher?