Concurrent and parallel programming is difficult due to the presence of memory side-effects, which may introduce data races. Type qualifiers, such as reference capabilities, can remove data races by restricting sharing of mutable data.

Unfortunately, reference capability languages are an all-in or nothing game, i.e., all the types must be annotated with reference capabilities. In this work in progress, we propose to mix the ideas from the reference capability literature with gradual typing, leading to gradual reference capabilities.