Some thoughts on skirting the line between static and dynamic typing - https://www.scattered-thoughts.net/writing/zest-dialects-and-metaprogramming/

Since you mention Julia: its approach to types is not very different from Common Lisp, meaning it’s well-known and well-documented. The types themselves are different though, with a much stronger emphasis on arrays.

The Carp language has a similar approach, of having a statically typed, compiled language, along with a dynamically typed more traditional lisp superset that can be used in the REPL and for metaprogramming.

Extempore has a similar layered approach in a scheme-like language to allow both high performance low-level code and quickly livecoded performance code to share the (super/sub- sets of) same underlying scheme-like language: https://github.com/digego/extempore