Chris

I think we could define some common interface between the local build cache and container registry. The registry would follow [this spec](https://github.com/opencontainers/distribution-spec/blob/main/spec.md#content-discovery). There is also probably some OCI spec on...

I like the idea of using directory color. Also generally use `rustfmt` and check any notable `clippy` suggestions.

Is there a use case for `run("")` - an actual empty layer? If not, maybe just default to this behaviour whenever we see `run("")`.

e.g. ```dockerfile FROM alpine RUN [] ``` I could be wrong but it does seem that `RUN []` does not produce a layer.

Yes, in a way. I could rewrite the expression parser to be more like parsing binary operators. Then at some point we'll have `alt((another_operator, parentheses_close_expression))` and if I `cut(alt(...))` then...

 Now it points to the problematic escape char at least. I think we can still improve by printing the possible escape chars, so I'll leave this issue open for...

Can you elaborate on this?

Useful doc on URL format https://github.com/bagder/docs/blob/master/URL-interop.md

@maowtm Is nested merge supported, or handled some way? e.g. `(run_literal::merge)::merge`. Currently seems to hang indefinitely after attempting to build with a nested merge, maybe something related to imagegen.