This RFC proposes a framework for making certain (top-level) declarations (e.g. type aliases) available in every Leo program without the need to write those declarations explicitly. These may be hardwired into the language or provided by standard libraries/packages; in the latter case, the libraries may be implicitly imported or required to be explicitly imported.
that can be readily used in programs. The initial motivation for this in Leo was to have a type alias `string` for character arrays of unspecified sizes (array types of unspecified sizes and type aliases are discussed in separate RFCs), but the feature is clearly more general.
it may make sense for any of the four kinds of declarations above to have built-in instances, i.e., we could have some built-in functions, circuit types, global constants, and type aliases. These features are why this RFC talks of built-in declarations, more broadly than just built-in type aliases that inspired it.
The built-in status of the envisioned declarations will be done through explicitly declared standard library(stdlib) files. Then these stdlib files must expressly be imported, except the files found in stdlib/prelude/*. The ones found in the prelude are features determined to be helpful enough in standard programs and are auto-imported.
