6.5 Exports: provide
(provide provide-spec )
A provide form can only appear at module level (i.e., in the immediate body of a module). Specifying multiple provide-specs in a single provide is exactly the same as using multiple provides each with a single provide-spec.
Each identifier can be exported at most once from a module across all provides within the module. More precisely, the external name for each export must be distinct; the same internal binding can be exported multiple times with different external names.
The allowed shape of a provide-spec is defined recursively:
In its simplest form, a provide-spec indicates a binding within its module to be exported. The binding can be from either a local definition, or from an import.
(rename-out [orig-id export-id] )
A rename-out form is similar to just specifying an identifier, but the exported binding orig-id is given a different name, export-id, to importing modules.
The all-defined-out shorthand exports all bindings that are defined within the exporting module (as opposed to imported).
Use of the all-defined-out shorthand is generally discouraged, because it makes less clear the actual exports for a module, and because PLT Scheme programmers get into the habit of thinking that definitions can be added freely to a module without affecting its public interface (which is not the case when all-defined-out is used).
The all-from-out shorthand exports all bindings in the module that were imported using a require-spec that is based on module-path.
Although different module-paths could refer to the same file-based module, re-exporting with all-from-out is based specifically on the module-path reference, and not the module that is actually referenced.
(except-out provide-spec id )
Like provide-spec, but omitting the export of each id, where id is the external name of the binding to omit.
(prefix-out prefix-id provide-spec)
Like provide-spec, but adding prefix-id to the beginning of the external name for each exported binding.